diff options
Diffstat (limited to 'target/linux/generic/patches-3.9/100-overlayfs.patch')
| -rw-r--r-- | target/linux/generic/patches-3.9/100-overlayfs.patch | 3244 |
1 files changed, 3244 insertions, 0 deletions
diff --git a/target/linux/generic/patches-3.9/100-overlayfs.patch b/target/linux/generic/patches-3.9/100-overlayfs.patch new file mode 100644 index 0000000000..2eda17b2cb --- /dev/null +++ b/target/linux/generic/patches-3.9/100-overlayfs.patch @@ -0,0 +1,3244 @@ +diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking +index 0706d32..4331290 100644 +--- a/Documentation/filesystems/Locking ++++ b/Documentation/filesystems/Locking +@@ -66,6 +66,7 @@ prototypes: + int (*atomic_open)(struct inode *, struct dentry *, + struct file *, unsigned open_flag, + umode_t create_mode, int *opened); ++ int (*dentry_open)(struct dentry *, struct file *, const struct cred *); + + locking rules: + all may block +@@ -93,6 +94,7 @@ removexattr: yes + fiemap: no + update_time: no + atomic_open: yes ++dentry_open: no + + Additionally, ->rmdir(), ->unlink() and ->rename() have ->i_mutex on + victim. +diff --git a/Documentation/filesystems/overlayfs.txt b/Documentation/filesystems/overlayfs.txt +new file mode 100644 +index 0000000..00dbab0 +--- /dev/null ++++ b/Documentation/filesystems/overlayfs.txt +@@ -0,0 +1,199 @@ ++Written by: Neil Brown <neilb@suse.de> ++ ++Overlay Filesystem ++================== ++ ++This document describes a prototype for a new approach to providing ++overlay-filesystem functionality in Linux (sometimes referred to as ++union-filesystems). An overlay-filesystem tries to present a ++filesystem which is the result over overlaying one filesystem on top ++of the other. ++ ++The result will inevitably fail to look exactly like a normal ++filesystem for various technical reasons. The expectation is that ++many use cases will be able to ignore these differences. ++ ++This approach is 'hybrid' because the objects that appear in the ++filesystem do not all appear to belong to that filesystem. In many ++cases an object accessed in the union will be indistinguishable ++from accessing the corresponding object from the original filesystem. ++This is most obvious from the 'st_dev' field returned by stat(2). ++ ++While directories will report an st_dev from the overlay-filesystem, ++all non-directory objects will report an st_dev from the lower or ++upper filesystem that is providing the object. Similarly st_ino will ++only be unique when combined with st_dev, and both of these can change ++over the lifetime of a non-directory object. Many applications and ++tools ignore these values and will not be affected. ++ ++Upper and Lower ++--------------- ++ ++An overlay filesystem combines two filesystems - an 'upper' filesystem ++and a 'lower' filesystem. When a name exists in both filesystems, the ++object in the 'upper' filesystem is visible while the object in the ++'lower' filesystem is either hidden or, in the case of directories, ++merged with the 'upper' object. ++ ++It would be more correct to refer to an upper and lower 'directory ++tree' rather than 'filesystem' as it is quite possible for both ++directory trees to be in the same filesystem and there is no ++requirement that the root of a filesystem be given for either upper or ++lower. ++ ++The lower filesystem can be any filesystem supported by Linux and does ++not need to be writable. The lower filesystem can even be another ++overlayfs. The upper filesystem will normally be writable and if it ++is it must support the creation of trusted.* extended attributes, and ++must provide valid d_type in readdir responses, at least for symbolic ++links - so NFS is not suitable. ++ ++A read-only overlay of two read-only filesystems may use any ++filesystem type. ++ ++Directories ++----------- ++ ++Overlaying mainly involves directories. If a given name appears in both ++upper and lower filesystems and refers to a non-directory in either, ++then the lower object is hidden - the name refers only to the upper ++object. ++ ++Where both upper and lower objects are directories, a merged directory ++is formed. ++ ++At mount time, the two directories given as mount options are combined ++into a merged directory: ++ ++ mount -t overlayfs overlayfs -olowerdir=/lower,upperdir=/upper /overlay ++ ++Then whenever a lookup is requested in such a merged directory, the ++lookup is performed in each actual directory and the combined result ++is cached in the dentry belonging to the overlay filesystem. If both ++actual lookups find directories, both are stored and a merged ++directory is created, otherwise only one is stored: the upper if it ++exists, else the lower. ++ ++Only the lists of names from directories are merged. Other content ++such as metadata and extended attributes are reported for the upper ++directory only. These attributes of the lower directory are hidden. ++ ++whiteouts and opaque directories ++-------------------------------- ++ ++In order to support rm and rmdir without changing the lower ++filesystem, an overlay filesystem needs to record in the upper filesystem ++that files have been removed. This is done using whiteouts and opaque ++directories (non-directories are always opaque). ++ ++The overlay filesystem uses extended attributes with a ++"trusted.overlay." prefix to record these details. ++ ++A whiteout is created as a symbolic link with target ++"(overlay-whiteout)" and with xattr "trusted.overlay.whiteout" set to "y". ++When a whiteout is found in the upper level of a merged directory, any ++matching name in the lower level is ignored, and the whiteout itself ++is also hidden. ++ ++A directory is made opaque by setting the xattr "trusted.overlay.opaque" ++to "y". Where the upper filesystem contains an opaque directory, any ++directory in the lower filesystem with the same name is ignored. ++ ++readdir ++------- ++ ++When a 'readdir' request is made on a merged directory, the upper and ++lower directories are each read and the name lists merged in the ++obvious way (upper is read first, then lower - entries that already ++exist are not re-added). This merged name list is cached in the ++'struct file' and so remains as long as the file is kept open. If the ++directory is opened and read by two processes at the same time, they ++will each have separate caches. A seekdir to the start of the ++directory (offset 0) followed by a readdir will cause the cache to be ++discarded and rebuilt. ++ ++This means that changes to the merged directory do not appear while a ++directory is being read. This is unlikely to be noticed by many ++programs. ++ ++seek offsets are assigned sequentially when the directories are read. ++Thus if ++ - read part of a directory ++ - remember an offset, and close the directory ++ - re-open the directory some time later ++ - seek to the remembered offset ++ ++there may be little correlation between the old and new locations in ++the list of filenames, particularly if anything has changed in the ++directory. ++ ++Readdir on directories that are not merged is simply handled by the ++underlying directory (upper or lower). ++ ++ ++Non-directories ++--------------- ++ ++Objects that are not directories (files, symlinks, device-special ++files etc.) are presented either from the upper or lower filesystem as ++appropriate. When a file in the lower filesystem is accessed in a way ++the requires write-access, such as opening for write access, changing ++some metadata etc., the file is first copied from the lower filesystem ++to the upper filesystem (copy_up). Note that creating a hard-link ++also requires copy_up, though of course creation of a symlink does ++not. ++ ++The copy_up may turn out to be unnecessary, for example if the file is ++opened for read-write but the data is not modified. ++ ++The copy_up process first makes sure that the containing directory ++exists in the upper filesystem - creating it and any parents as ++necessary. It then creates the object with the same metadata (owner, ++mode, mtime, symlink-target etc.) and then if the object is a file, the ++data is copied from the lower to the upper filesystem. Finally any ++extended attributes are copied up. ++ ++Once the copy_up is complete, the overlay filesystem simply ++provides direct access to the newly created file in the upper ++filesystem - future operations on the file are barely noticed by the ++overlay filesystem (though an operation on the name of the file such as ++rename or unlink will of course be noticed and handled). ++ ++ ++Non-standard behavior ++--------------------- ++ ++The copy_up operation essentially creates a new, identical file and ++moves it over to the old name. The new file may be on a different ++filesystem, so both st_dev and st_ino of the file may change. ++ ++Any open files referring to this inode will access the old data and ++metadata. Similarly any file locks obtained before copy_up will not ++apply to the copied up file. ++ ++On a file opened with O_RDONLY fchmod(2), fchown(2), futimesat(2) and ++fsetxattr(2) will fail with EROFS. ++ ++If a file with multiple hard links is copied up, then this will ++"break" the link. Changes will not be propagated to other names ++referring to the same inode. ++ ++Symlinks in /proc/PID/ and /proc/PID/fd which point to a non-directory ++object in overlayfs will not contain valid absolute paths, only ++relative paths leading up to the filesystem's root. This will be ++fixed in the future. ++ ++Some operations are not atomic, for example a crash during copy_up or ++rename will leave the filesystem in an inconsistent state. This will ++be addressed in the future. ++ ++Changes to underlying filesystems ++--------------------------------- ++ ++Offline changes, when the overlay is not mounted, are allowed to either ++the upper or the lower trees. ++ ++Changes to the underlying filesystems while part of a mounted overlay ++filesystem are not allowed. If the underlying filesystem is changed, ++the behavior of the overlay is undefined, though it will not result in ++a crash or deadlock. +diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt +index bc4b06b..f64a4d1 100644 +--- a/Documentation/filesystems/vfs.txt ++++ b/Documentation/filesystems/vfs.txt +@@ -362,6 +362,7 @@ struct inode_operations { + int (*atomic_open)(struct inode *, struct dentry *, + struct file *, unsigned open_flag, + umode_t create_mode, int *opened); ++ int (*dentry_open)(struct dentry *, struct file *, const struct cred *); + }; + + Again, all methods are called without any locks being held, unless +@@ -681,6 +682,12 @@ struct address_space_operations { + but instead uses bmap to find out where the blocks in the file + are and uses those addresses directly. + ++ dentry_open: this is an alternative to f_op->open(), the difference is that ++ this method may open a file not necessarily originating from the same ++ filesystem as the one i_op->open() was called on. It may be ++ useful for stacking filesystems which want to allow native I/O directly ++ on underlying files. ++ + + invalidatepage: If a page has PagePrivate set, then invalidatepage + will be called when part or all of the page is to be removed +diff --git a/MAINTAINERS b/MAINTAINERS +index 9561658..9ea89b8 100644 +--- a/MAINTAINERS ++++ b/MAINTAINERS +@@ -5872,6 +5872,13 @@ F: drivers/scsi/osd/ + F: include/scsi/osd_* + F: fs/exofs/ + ++OVERLAYFS FILESYSTEM ++M: Miklos Szeredi <miklos@szeredi.hu> ++L: linux-fsdevel@vger.kernel.org ++S: Supported ++F: fs/overlayfs/* ++F: Documentation/filesystems/overlayfs.txt ++ + P54 WIRELESS DRIVER + M: Christian Lamparter <chunkeey@googlemail.com> + L: linux-wireless@vger.kernel.org +diff --git a/fs/Kconfig b/fs/Kconfig +index 780725a..9e2ccd5 100644 +--- a/fs/Kconfig ++++ b/fs/Kconfig +@@ -67,6 +67,7 @@ source "fs/quota/Kconfig" + + source "fs/autofs4/Kconfig" + source "fs/fuse/Kconfig" ++source "fs/overlayfs/Kconfig" + + config GENERIC_ACL + bool +diff --git a/fs/Makefile b/fs/Makefile +index 9d53192..479a720 100644 +--- a/fs/Makefile ++++ b/fs/Makefile +@@ -107,6 +107,7 @@ obj-$(CONFIG_QNX6FS_FS) += qnx6/ + obj-$(CONFIG_AUTOFS4_FS) += autofs4/ + obj-$(CONFIG_ADFS_FS) += adfs/ + obj-$(CONFIG_FUSE_FS) += fuse/ ++obj-$(CONFIG_OVERLAYFS_FS) += overlayfs/ + obj-$(CONFIG_UDF_FS) += udf/ + obj-$(CONFIG_SUN_OPENPROMFS) += openpromfs/ + obj-$(CONFIG_OMFS_FS) += omfs/ +diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c +index e924cf4..8f7551e 100644 +--- a/fs/ecryptfs/main.c ++++ b/fs/ecryptfs/main.c +@@ -567,6 +567,13 @@ static struct dentry *ecryptfs_mount(struct file_system_type *fs_type, int flags + s->s_maxbytes = path.dentry->d_sb->s_maxbytes; + s->s_blocksize = path.dentry->d_sb->s_blocksize; + s->s_magic = ECRYPTFS_SUPER_MAGIC; ++ s->s_stack_depth = path.dentry->d_sb->s_stack_depth + 1; ++ ++ rc = -EINVAL; ++ if (s->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) { ++ printk(KERN_ERR "eCryptfs: maximum fs stacking depth exceeded\n"); ++ goto out_free; ++ } + + inode = ecryptfs_get_inode(path.dentry->d_inode, s); + rc = PTR_ERR(inode); +diff --git a/fs/internal.h b/fs/internal.h +index 507141f..89481ac 100644 +--- a/fs/internal.h ++++ b/fs/internal.h +@@ -42,11 +42,6 @@ static inline int __sync_blockdev(struct block_device *bdev, int wait) + extern void __init chrdev_init(void); + + /* +- * namei.c +- */ +-extern int __inode_permission(struct inode *, int); +- +-/* + * namespace.c + */ + extern int copy_mount_options(const void __user *, unsigned long *); +diff --git a/fs/namei.c b/fs/namei.c +index 57ae9c8..e1cffbd 100644 +--- a/fs/namei.c ++++ b/fs/namei.c +@@ -402,6 +402,7 @@ int __inode_permission(struct inode *inode, int mask) + + return security_inode_permission(inode, mask); + } ++EXPORT_SYMBOL(__inode_permission); + + /** + * sb_permission - Check superblock-level permissions +@@ -2867,9 +2868,12 @@ finish_open_created: + error = may_open(&nd->path, acc_mode, open_flag); + if (error) + goto out; +- file->f_path.mnt = nd->path.mnt; +- error = finish_open(file, nd->path.dentry, NULL, opened); +- if (error) { ++ ++ BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ ++ error = vfs_open(&nd->path, file, current_cred()); ++ if (!error) { ++ *opened |= FILE_OPENED; ++ } else { + if (error == -EOPENSTALE) + goto stale_open; + goto out; +diff --git a/fs/namespace.c b/fs/namespace.c +index 50ca17d..9791b4e 100644 +--- a/fs/namespace.c ++++ b/fs/namespace.c +@@ -1399,6 +1399,24 @@ void drop_collected_mounts(struct vfsmount *mnt) + release_mounts(&umount_list); + } + ++struct vfsmount *clone_private_mount(struct path *path) ++{ ++ struct mount *old_mnt = real_mount(path->mnt); ++ struct mount *new_mnt; ++ ++ if (IS_MNT_UNBINDABLE(old_mnt)) ++ return ERR_PTR(-EINVAL); ++ ++ down_read(&namespace_sem); ++ new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE); ++ up_read(&namespace_sem); ++ if (!new_mnt) ++ return ERR_PTR(-ENOMEM); ++ ++ return &new_mnt->mnt; ++} ++EXPORT_SYMBOL_GPL(clone_private_mount); ++ + int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg, + struct vfsmount *root) + { +diff --git a/fs/open.c b/fs/open.c +index 6835446..b9d9f9e 100644 +--- a/fs/open.c ++++ b/fs/open.c +@@ -828,8 +828,7 @@ struct file *dentry_open(const struct path *path, int flags, + f = get_empty_filp(); + if (!IS_ERR(f)) { + f->f_flags = flags; +- f->f_path = *path; +- error = do_dentry_open(f, NULL, cred); ++ error = vfs_open(path, f, cred); + if (!error) { + /* from now on we need fput() to dispose of f */ + error = open_check_o_direct(f); +@@ -846,6 +845,26 @@ struct file *dentry_open(const struct path *path, int flags, + } + EXPORT_SYMBOL(dentry_open); + ++/** ++ * vfs_open - open the file at the given path ++ * @path: path to open ++ * @filp: newly allocated file with f_flag initialized ++ * @cred: credentials to use ++ */ ++int vfs_open(const struct path *path, struct file *filp, ++ const struct cred *cred) ++{ ++ struct inode *inode = path->dentry->d_inode; ++ ++ if (inode->i_op->dentry_open) ++ return inode->i_op->dentry_open(path->dentry, filp, cred); ++ else { ++ filp->f_path = *path; ++ return do_dentry_open(filp, NULL, cred); ++ } ++} ++EXPORT_SYMBOL(vfs_open); ++ + static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op) + { + int lookup_flags = 0; +diff --git a/fs/overlayfs/Kconfig b/fs/overlayfs/Kconfig +new file mode 100644 +index 0000000..c4517da +--- /dev/null ++++ b/fs/overlayfs/Kconfig +@@ -0,0 +1,4 @@ ++config OVERLAYFS_FS ++ tristate "Overlay filesystem support" ++ help ++ Add support for overlay filesystem. +diff --git a/fs/overlayfs/Makefile b/fs/overlayfs/Makefile +new file mode 100644 +index 0000000..8f91889 +--- /dev/null ++++ b/fs/overlayfs/Makefile +@@ -0,0 +1,7 @@ ++# ++# Makefile for the overlay filesystem. ++# ++ ++obj-$(CONFIG_OVERLAYFS_FS) += overlayfs.o ++ ++overlayfs-objs := super.o inode.o dir.o readdir.o copy_up.o +diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c +new file mode 100644 +index 0000000..eef85e0 +--- /dev/null ++++ b/fs/overlayfs/copy_up.c +@@ -0,0 +1,385 @@ ++/* ++ * ++ * Copyright (C) 2011 Novell Inc. ++ * ++ * This program is free software; you can redistribute it and/or modify it ++ * under the terms of the GNU General Public License version 2 as published by ++ * the Free Software Foundation. ++ */ ++ ++#include <linux/fs.h> ++#include <linux/slab.h> ++#include <linux/file.h> ++#include <linux/splice.h> ++#include <linux/xattr.h> ++#include <linux/security.h> ++#include <linux/uaccess.h> ++#include <linux/sched.h> ++#include "overlayfs.h" ++ ++#define OVL_COPY_UP_CHUNK_SIZE (1 << 20) ++ ++static int ovl_copy_up_xattr(struct dentry *old, struct dentry *new) ++{ ++ ssize_t list_size, size; ++ char *buf, *name, *value; ++ int error; ++ ++ if (!old->d_inode->i_op->getxattr || ++ !new->d_inode->i_op->getxattr) ++ return 0; ++ ++ list_size = vfs_listxattr(old, NULL, 0); ++ if (list_size <= 0) { ++ if (list_size == -EOPNOTSUPP) ++ return 0; ++ return list_size; ++ } ++ ++ buf = kzalloc(list_size, GFP_KERNEL); ++ if (!buf) ++ return -ENOMEM; ++ ++ error = -ENOMEM; ++ value = kmalloc(XATTR_SIZE_MAX, GFP_KERNEL); ++ if (!value) ++ goto out; ++ ++ list_size = vfs_listxattr(old, buf, list_size); ++ if (list_size <= 0) { ++ error = list_size; ++ goto out_free_value; ++ } ++ ++ for (name = buf; name < (buf + list_size); name += strlen(name) + 1) { ++ size = vfs_getxattr(old, name, value, XATTR_SIZE_MAX); ++ if (size <= 0) { ++ error = size; ++ goto out_free_value; ++ } ++ error = vfs_setxattr(new, name, value, size, 0); ++ if (error) ++ goto out_free_value; ++ } ++ ++out_free_value: ++ kfree(value); ++out: ++ kfree(buf); ++ return error; ++} ++ ++static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len) ++{ ++ struct file *old_file; ++ struct file *new_file; ++ int error = 0; ++ ++ if (len == 0) ++ return 0; ++ ++ old_file = ovl_path_open(old, O_RDONLY); ++ if (IS_ERR(old_file)) ++ return PTR_ERR(old_file); ++ ++ new_file = ovl_path_open(new, O_WRONLY); ++ if (IS_ERR(new_file)) { ++ error = PTR_ERR(new_file); ++ goto out_fput; ++ } ++ ++ /* FIXME: copy up sparse files efficiently */ ++ while (len) { ++ loff_t offset = new_file->f_pos; ++ size_t this_len = OVL_COPY_UP_CHUNK_SIZE; ++ long bytes; ++ ++ if (len < this_len) ++ this_len = len; ++ ++ if (signal_pending_state(TASK_KILLABLE, current)) { ++ error = -EINTR; ++ break; ++ } ++ ++ bytes = do_splice_direct(old_file, &offset, new_file, this_len, ++ SPLICE_F_MOVE); ++ if (bytes <= 0) { ++ error = bytes; ++ break; ++ } ++ ++ len -= bytes; ++ } ++ ++ fput(new_file); ++out_fput: ++ fput(old_file); ++ return error; ++} ++ ++static char *ovl_read_symlink(struct dentry *realdentry) ++{ ++ int res; ++ char *buf; ++ struct inode *inode = realdentry->d_inode; ++ mm_segment_t old_fs; ++ ++ res = -EINVAL; ++ if (!inode->i_op->readlink) ++ goto err; ++ ++ res = -ENOMEM; ++ buf = (char *) __get_free_page(GFP_KERNEL); ++ if (!buf) ++ goto err; ++ ++ old_fs = get_fs(); ++ set_fs(get_ds()); ++ /* The cast to a user pointer is valid due to the set_fs() */ ++ res = inode->i_op->readlink(realdentry, ++ (char __user *)buf, PAGE_SIZE - 1); ++ set_fs(old_fs); ++ if (res < 0) { ++ free_page((unsigned long) buf); ++ goto err; ++ } ++ buf[res] = '\0'; ++ ++ return buf; ++ ++err: ++ return ERR_PTR(res); ++} ++ ++static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat) ++{ ++ struct iattr attr = { ++ .ia_valid = ++ ATTR_ATIME | ATTR_MTIME | ATTR_ATIME_SET | ATTR_MTIME_SET, ++ .ia_atime = stat->atime, ++ .ia_mtime = stat->mtime, ++ }; ++ ++ return notify_change(upperdentry, &attr); ++} ++ ++static int ovl_set_mode(struct dentry *upperdentry, umode_t mode) ++{ ++ struct iattr attr = { ++ .ia_valid = ATTR_MODE, ++ .ia_mode = mode, ++ }; ++ ++ return notify_change(upperdentry, &attr); ++} ++ ++static int ovl_copy_up_locked(struct dentry *upperdir, struct dentry *dentry, ++ struct path *lowerpath, struct kstat *stat, ++ const char *link) ++{ ++ int err; ++ struct path newpath; ++ umode_t mode = stat->mode; ++ ++ /* Can't properly set mode on creation because of the umask */ ++ stat->mode &= S_IFMT; ++ ++ ovl_path_upper(dentry, &newpath); ++ WARN_ON(newpath.dentry); ++ newpath.dentry = ovl_upper_create(upperdir, dentry, stat, link); ++ if (IS_ERR(newpath.dentry)) ++ return PTR_ERR(newpath.dentry); ++ ++ if (S_ISREG(stat->mode)) { ++ err = ovl_copy_up_data(lowerpath, &newpath, stat->size); ++ if (err) ++ goto err_remove; ++ } ++ ++ err = ovl_copy_up_xattr(lowerpath->dentry, newpath.dentry); ++ if (err) ++ goto err_remove; ++ ++ mutex_lock(&newpath.dentry->d_inode->i_mutex); ++ if (!S_ISLNK(stat->mode)) ++ err = ovl_set_mode(newpath.dentry, mode); ++ if (!err) ++ err = ovl_set_timestamps(newpath.dentry, stat); ++ mutex_unlock(&newpath.dentry->d_inode->i_mutex); ++ if (err) ++ goto err_remove; ++ ++ ovl_dentry_update(dentry, newpath.dentry); ++ ++ /* ++ * Easiest way to get rid of the lower dentry reference is to ++ * drop this dentry. This is neither needed nor possible for ++ * directories. ++ */ ++ if (!S_ISDIR(stat->mode)) ++ d_drop(dentry); ++ ++ return 0; ++ ++err_remove: ++ if (S_ISDIR(stat->mode)) ++ vfs_rmdir(upperdir->d_inode, newpath.dentry); ++ else ++ vfs_unlink(upperdir->d_inode, newpath.dentry); ++ ++ dput(newpath.dentry); ++ ++ return err; ++} ++ ++/* ++ * Copy up a single dentry ++ * ++ * Directory renames only allowed on "pure upper" (already created on ++ * upper filesystem, never copied up). Directories which are on lower or ++ * are merged may not be renamed. For these -EXDEV is returned and ++ * userspace has to deal with it. This means, when copying up a ++ * directory we can rely on it and ancestors being stable. ++ * ++ * Non-directory renames start with copy up of source if necessary. The ++ * actual rename will only proceed once the copy up was successful. Copy ++ * up uses upper parent i_mutex for exclusion. Since rename can change ++ * d_parent it is possible that the copy up will lock the old parent. At ++ * that point the file will have already been copied up anyway. ++ */ ++static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry, ++ struct path *lowerpath, struct kstat *stat) ++{ ++ int err; ++ struct kstat pstat; ++ struct path parentpath; ++ struct dentry *upperdir; ++ const struct cred *old_cred; ++ struct cred *override_cred; ++ char *link = NULL; ++ ++ ovl_path_upper(parent, &parentpath); ++ upperdir = parentpath.dentry; ++ ++ err = vfs_getattr(&parentpath, &pstat); ++ if (err) ++ return err; ++ ++ if (S_ISLNK(stat->mode)) { ++ link = ovl_read_symlink(lowerpath->dentry); ++ if (IS_ERR(link)) ++ return PTR_ERR(link); ++ } ++ ++ err = -ENOMEM; ++ override_cred = prepare_creds(); ++ if (!override_cred) ++ goto out_free_link; ++ ++ override_cred->fsuid = stat->uid; ++ override_cred->fsgid = stat->gid; ++ /* ++ * CAP_SYS_ADMIN for copying up extended attributes ++ * CAP_DAC_OVERRIDE for create ++ * CAP_FOWNER for chmod, timestamp update ++ * CAP_FSETID for chmod ++ * CAP_MKNOD for mknod ++ */ ++ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); ++ cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); ++ cap_raise(override_cred->cap_effective, CAP_FOWNER); ++ cap_raise(override_cred->cap_effective, CAP_FSETID); ++ cap_raise(override_cred->cap_effective, CAP_MKNOD); ++ old_cred = override_creds(override_cred); ++ ++ mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT); ++ if (ovl_path_type(dentry) != OVL_PATH_LOWER) { ++ err = 0; ++ } else { ++ err = ovl_copy_up_locked(upperdir, dentry, lowerpath, ++ stat, link); ++ if (!err) { ++ /* Restore timestamps on parent (best effort) */ ++ ovl_set_timestamps(upperdir, &pstat); ++ } ++ } ++ ++ mutex_unlock(&upperdir->d_inode->i_mutex); ++ ++ revert_creds(old_cred); ++ put_cred(override_cred); ++ ++out_free_link: ++ if (link) ++ free_page((unsigned long) link); ++ ++ return err; ++} ++ ++int ovl_copy_up(struct dentry *dentry) ++{ ++ int err; ++ ++ err = 0; ++ while (!err) { ++ struct dentry *next; ++ struct dentry *parent; ++ struct path lowerpath; ++ struct kstat stat; ++ enum ovl_path_type type = ovl_path_type(dentry); ++ ++ if (type != OVL_PATH_LOWER) ++ break; ++ ++ next = dget(dentry); ++ /* find the topmost dentry not yet copied up */ ++ for (;;) { ++ parent = dget_parent(next); ++ ++ type = ovl_path_type(parent); ++ if (type != OVL_PATH_LOWER) ++ break; ++ ++ dput(next); ++ next = parent; ++ } ++ ++ ovl_path_lower(next, &lowerpath); ++ err = vfs_getattr(&lowerpath, &stat); ++ if (!err) ++ err = ovl_copy_up_one(parent, next, &lowerpath, &stat); ++ ++ dput(parent); ++ dput(next); ++ } ++ ++ return err; ++} ++ ++/* Optimize by not copying up the file first and truncating later */ ++int ovl_copy_up_truncate(struct dentry *dentry, loff_t size) ++{ ++ int err; ++ struct kstat stat; ++ struct path lowerpath; ++ struct dentry *parent = dget_parent(dentry); ++ ++ err = ovl_copy_up(parent); ++ if (err) ++ goto out_dput_parent; ++ ++ ovl_path_lower(dentry, &lowerpath); ++ err = vfs_getattr(&lowerpath, &stat); ++ if (err) ++ goto out_dput_parent; ++ ++ if (size < stat.size) ++ stat.size = size; ++ ++ err = ovl_copy_up_one(parent, dentry, &lowerpath, &stat); ++ ++out_dput_parent: ++ dput(parent); ++ return err; ++} +diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c +new file mode 100644 +index 0000000..b530e56 +--- /dev/null ++++ b/fs/overlayfs/dir.c +@@ -0,0 +1,604 @@ ++/* ++ * ++ * Copyright (C) 2011 Novell Inc. ++ * ++ * This program is free software; you can redistribute it and/or modify it ++ * under the terms of the GNU General Public License version 2 as published by ++ * the Free Software Foundation. ++ */ ++ ++#include <linux/fs.h> ++#include <linux/namei.h> ++#include <linux/xattr.h> ++#include <linux/security.h> ++#include <linux/cred.h> ++#include "overlayfs.h" ++ ++static const char *ovl_whiteout_symlink = "(overlay-whiteout)"; ++ ++static int ovl_whiteout(struct dentry *upperdir, struct dentry *dentry) ++{ ++ int err; ++ struct dentry *newdentry; ++ const struct cred *old_cred; ++ struct cred *override_cred; ++ ++ /* FIXME: recheck lower dentry to see if whiteout is really needed */ ++ ++ err = -ENOMEM; ++ override_cred = prepare_creds(); ++ if (!override_cred) ++ goto out; ++ ++ /* ++ * CAP_SYS_ADMIN for setxattr ++ * CAP_DAC_OVERRIDE for symlink creation ++ * CAP_FOWNER for unlink in sticky directory ++ */ ++ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); ++ cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); ++ cap_raise(override_cred->cap_effective, CAP_FOWNER); ++ override_cred->fsuid = GLOBAL_ROOT_UID; ++ override_cred->fsgid = GLOBAL_ROOT_GID; ++ old_cred = override_creds(override_cred); ++ ++ newdentry = lookup_one_len(dentry->d_name.name, upperdir, ++ dentry->d_name.len); ++ err = PTR_ERR(newdentry); ++ if (IS_ERR(newdentry)) ++ goto out_put_cred; ++ ++ /* Just been removed within the same locked region */ ++ WARN_ON(newdentry->d_inode); ++ ++ err = vfs_symlink(upperdir->d_inode, newdentry, ovl_whiteout_symlink); ++ if (err) ++ goto out_dput; ++ ++ ovl_dentry_version_inc(dentry->d_parent); ++ ++ err = vfs_setxattr(newdentry, ovl_whiteout_xattr, "y", 1, 0); ++ if (err) ++ vfs_unlink(upperdir->d_inode, newdentry); ++ ++out_dput: ++ dput(newdentry); ++out_put_cred: ++ revert_creds(old_cred); ++ put_cred(override_cred); ++out: ++ if (err) { ++ /* ++ * There's no way to recover from failure to whiteout. ++ * What should we do? Log a big fat error and... ? ++ */ ++ printk(KERN_ERR "overlayfs: ERROR - failed to whiteout '%s'\n", ++ dentry->d_name.name); ++ } ++ ++ return err; ++} ++ ++static struct dentry *ovl_lookup_create(struct dentry *upperdir, ++ struct dentry *template) ++{ ++ int err; ++ struct dentry *newdentry; ++ struct qstr *name = &template->d_name; ++ ++ newdentry = lookup_one_len(name->name, upperdir, name->len); ++ if (IS_ERR(newdentry)) ++ return newdentry; ++ ++ if (newdentry->d_inode) { ++ const struct cred *old_cred; ++ struct cred *override_cred; ++ ++ /* No need to check whiteout if lower parent is non-existent */ ++ err = -EEXIST; ++ if (!ovl_dentry_lower(template->d_parent)) ++ goto out_dput; ++ ++ if (!S_ISLNK(newdentry->d_inode->i_mode)) ++ goto out_dput; ++ ++ err = -ENOMEM; ++ override_cred = prepare_creds(); ++ if (!override_cred) ++ goto out_dput; ++ ++ /* ++ * CAP_SYS_ADMIN for getxattr ++ * CAP_FOWNER for unlink in sticky directory ++ */ ++ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); ++ cap_raise(override_cred->cap_effective, CAP_FOWNER); ++ old_cred = override_creds(override_cred); ++ ++ err = -EEXIST; ++ if (ovl_is_whiteout(newdentry)) ++ err = vfs_unlink(upperdir->d_inode, newdentry); ++ ++ revert_creds(old_cred); ++ put_cred(override_cred); ++ if (err) ++ goto out_dput; ++ ++ dput(newdentry); ++ newdentry = lookup_one_len(name->name, upperdir, name->len); ++ if (IS_ERR(newdentry)) { ++ ovl_whiteout(upperdir, template); ++ return newdentry; ++ } ++ ++ /* ++ * Whiteout just been successfully removed, parent ++ * i_mutex is still held, there's no way the lookup ++ * could return positive. ++ */ ++ WARN_ON(newdentry->d_inode); ++ } ++ ++ return newdentry; ++ ++out_dput: ++ dput(newdentry); ++ return ERR_PTR(err); ++} ++ ++struct dentry *ovl_upper_create(struct dentry *upperdir, struct dentry *dentry, ++ struct kstat *stat, const char *link) ++{ ++ int err; ++ struct dentry *newdentry; ++ struct inode *dir = upperdir->d_inode; ++ ++ newdentry = ovl_lookup_create(upperdir, dentry); ++ if (IS_ERR(newdentry)) ++ goto out; ++ ++ switch (stat->mode & S_IFMT) { ++ case S_IFREG: ++ err = vfs_create(dir, newdentry, stat->mode, NULL); ++ break; ++ ++ case S_IFDIR: ++ err = vfs_mkdir(dir, newdentry, stat->mode); ++ break; ++ ++ case S_IFCHR: ++ case S_IFBLK: ++ case S_IFIFO: ++ case S_IFSOCK: ++ err = vfs_mknod(dir, newdentry, stat->mode, stat->rdev); ++ break; ++ ++ case S_IFLNK: ++ err = vfs_symlink(dir, newdentry, link); ++ break; ++ ++ default: ++ err = -EPERM; ++ } ++ if (err) { ++ if (ovl_dentry_is_opaque(dentry)) ++ ovl_whiteout(upperdir, dentry); ++ dput(newdentry); ++ newdentry = ERR_PTR(err); ++ } else if (WARN_ON(!newdentry->d_inode)) { ++ /* ++ * Not quite sure if non-instantiated dentry is legal or not. ++ * VFS doesn't seem to care so check and warn here. ++ */ ++ dput(newdentry); ++ newdentry = ERR_PTR(-ENOENT); ++ } ++ ++out: ++ return newdentry; ++ ++} ++ ++static int ovl_set_opaque(struct dentry *upperdentry) ++{ ++ int err; ++ const struct cred *old_cred; ++ struct cred *override_cred; ++ ++ override_cred = prepare_creds(); ++ if (!override_cred) ++ return -ENOMEM; ++ ++ /* CAP_SYS_ADMIN for setxattr of "trusted" namespace */ ++ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); ++ old_cred = override_creds(override_cred); ++ err = vfs_setxattr(upperdentry, ovl_opaque_xattr, "y", 1, 0); ++ revert_creds(old_cred); ++ put_cred(override_cred); ++ ++ return err; ++} ++ ++static int ovl_remove_opaque(struct dentry *upperdentry) ++{ ++ int err; ++ const struct cred *old_cred; ++ struct cred *override_cred; ++ ++ override_cred = prepare_creds(); ++ if (!override_cred) ++ return -ENOMEM; ++ ++ /* CAP_SYS_ADMIN for removexattr of "trusted" namespace */ ++ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); ++ old_cred = override_creds(override_cred); ++ err = vfs_removexattr(upperdentry, ovl_opaque_xattr); ++ revert_creds(old_cred); ++ put_cred(override_cred); ++ ++ return err; ++} ++ ++static int ovl_dir_getattr(struct vfsmount *mnt, struct dentry *dentry, ++ struct kstat *stat) ++{ ++ int err; ++ enum ovl_path_type type; ++ struct path realpath; ++ ++ type = ovl_path_real(dentry, &realpath); ++ err = vfs_getattr(&realpath, stat); ++ if (err) ++ return err; ++ ++ stat->dev = dentry->d_sb->s_dev; ++ stat->ino = dentry->d_inode->i_ino; ++ ++ /* ++ * It's probably not worth it to count subdirs to get the ++ * correct link count. nlink=1 seems to pacify 'find' and ++ * other utilities. ++ */ ++ if (type == OVL_PATH_MERGE) ++ stat->nlink = 1; ++ ++ return 0; ++} ++ ++static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev, ++ const char *link) ++{ ++ int err; ++ struct dentry *newdentry; ++ struct dentry *upperdir; ++ struct inode *inode; ++ struct kstat stat = { ++ .mode = mode, ++ .rdev = rdev, ++ }; ++ ++ err = -ENOMEM; ++ inode = ovl_new_inode(dentry->d_sb, mode, dentry->d_fsdata); ++ if (!inode) ++ goto out; ++ ++ err = ovl_copy_up(dentry->d_parent); ++ if (err) ++ goto out_iput; ++ ++ upperdir = ovl_dentry_upper(dentry->d_parent); ++ mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT); ++ ++ newdentry = ovl_upper_create(upperdir, dentry, &stat, link); ++ err = PTR_ERR(newdentry); ++ if (IS_ERR(newdentry)) ++ goto out_unlock; ++ ++ ovl_dentry_version_inc(dentry->d_parent); ++ if (ovl_dentry_is_opaque(dentry) && S_ISDIR(mode)) { ++ err = ovl_set_opaque(newdentry); ++ if (err) { ++ vfs_rmdir(upperdir->d_inode, newdentry); ++ ovl_whiteout(upperdir, dentry); ++ goto out_dput; ++ } ++ } ++ ovl_dentry_update(dentry, newdentry); ++ ovl_copyattr(newdentry->d_inode, inode); ++ d_instantiate(dentry, inode); ++ inode = NULL; ++ newdentry = NULL; ++ err = 0; ++ ++out_dput: ++ dput(newdentry); ++out_unlock: ++ mutex_unlock(&upperdir->d_inode->i_mutex); ++out_iput: ++ iput(inode); ++out: ++ return err; ++} ++ ++static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode, ++ bool excl) ++{ ++ return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL); ++} ++ ++static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) ++{ ++ return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL); ++} ++ ++static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, ++ dev_t rdev) ++{ ++ return ovl_create_object(dentry, mode, rdev, NULL); ++} ++ ++static int ovl_symlink(struct inode *dir, struct dentry *dentry, ++ const char *link) ++{ ++ return ovl_create_object(dentry, S_IFLNK, 0, link); ++} ++ ++static int ovl_do_remove(struct dentry *dentry, bool is_dir) ++{ ++ int err; ++ enum ovl_path_type type; ++ struct path realpath; ++ struct dentry *upperdir; ++ ++ err = ovl_copy_up(dentry->d_parent); ++ if (err) ++ return err; ++ ++ upperdir = ovl_dentry_upper(dentry->d_parent); ++ mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT); ++ type = ovl_path_real(dentry, &realpath); ++ if (type != OVL_PATH_LOWER) { ++ err = -ESTALE; ++ if (realpath.dentry->d_parent != upperdir) ++ goto out_d_drop; ++ ++ /* FIXME: create whiteout up front and rename to target */ ++ ++ if (is_dir) ++ err = vfs_rmdir(upperdir->d_inode, realpath.dentry); ++ else ++ err = vfs_unlink(upperdir->d_inode, realpath.dentry); ++ if (err) ++ goto out_d_drop; ++ ++ ovl_dentry_version_inc(dentry->d_parent); ++ } ++ ++ if (type != OVL_PATH_UPPER || ovl_dentry_is_opaque(dentry)) ++ err = ovl_whiteout(upperdir, dentry); ++ ++ /* ++ * Keeping this dentry hashed would mean having to release ++ * upperpath/lowerpath, which could only be done if we are the ++ * sole user of this dentry. Too tricky... Just unhash for ++ * now. ++ */ ++out_d_drop: ++ d_drop(dentry); ++ mutex_unlock(&upperdir->d_inode->i_mutex); ++ ++ return err; ++} ++ ++static int ovl_unlink(struct inode *dir, struct dentry *dentry) ++{ ++ return ovl_do_remove(dentry, false); ++} ++ ++ ++static int ovl_rmdir(struct inode *dir, struct dentry *dentry) ++{ ++ int err; ++ enum ovl_path_type type; ++ ++ type = ovl_path_type(dentry); ++ if (type != OVL_PATH_UPPER) { ++ err = ovl_check_empty_and_clear(dentry, type); ++ if (err) ++ return err; ++ } ++ ++ return ovl_do_remove(dentry, true); ++} ++ ++static int ovl_link(struct dentry *old, struct inode *newdir, ++ struct dentry *new) ++{ ++ int err; ++ struct dentry *olddentry; ++ struct dentry *newdentry; ++ struct dentry *upperdir; ++ struct inode *newinode; ++ ++ err = ovl_copy_up(old); ++ if (err) ++ goto out; ++ ++ err = ovl_copy_up(new->d_parent); ++ if (err) ++ goto out; ++ ++ upperdir = ovl_dentry_upper(new->d_parent); ++ mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT); ++ newdentry = ovl_lookup_create(upperdir, new); ++ err = PTR_ERR(newdentry); ++ if (IS_ERR(newdentry)) ++ goto out_unlock; ++ ++ olddentry = ovl_dentry_upper(old); ++ err = vfs_link(olddentry, upperdir->d_inode, newdentry); ++ if (!err) { ++ if (WARN_ON(!newdentry->d_inode)) { ++ dput(newdentry); ++ err = -ENOENT; ++ goto out_unlock; ++ } ++ newinode = ovl_new_inode(old->d_sb, newdentry->d_inode->i_mode, ++ new->d_fsdata); ++ if (!newinode) ++ goto link_fail; ++ ovl_copyattr(upperdir->d_inode, newinode); ++ ++ ovl_dentry_version_inc(new->d_parent); ++ ovl_dentry_update(new, newdentry); ++ ++ d_instantiate(new, newinode); ++ } else { ++link_fail: ++ if (ovl_dentry_is_opaque(new)) ++ ovl_whiteout(upperdir, new); ++ dput(newdentry); ++ } ++out_unlock: ++ mutex_unlock(&upperdir->d_inode->i_mutex); ++out: ++ return err; ++ ++} ++ ++static int ovl_rename(struct inode *olddir, struct dentry *old, ++ struct inode *newdir, struct dentry *new) ++{ ++ int err; ++ enum ovl_path_type old_type; ++ enum ovl_path_type new_type; ++ struct dentry *old_upperdir; ++ struct dentry *new_upperdir; ++ struct dentry *olddentry; ++ struct dentry *newdentry; ++ struct dentry *trap; ++ bool old_opaque; ++ bool new_opaque; ++ bool new_create = false; ++ bool is_dir = S_ISDIR(old->d_inode->i_mode); ++ ++ /* Don't copy up directory trees */ ++ old_type = ovl_path_type(old); ++ if (old_type != OVL_PATH_UPPER && is_dir) ++ return -EXDEV; ++ ++ if (new->d_inode) { ++ new_type = ovl_path_type(new); ++ ++ if (new_type == OVL_PATH_LOWER && old_type == OVL_PATH_LOWER) { ++ if (ovl_dentry_lower(old)->d_inode == ++ ovl_dentry_lower(new)->d_inode) ++ return 0; ++ } ++ if (new_type != OVL_PATH_LOWER && old_type != OVL_PATH_LOWER) { ++ if (ovl_dentry_upper(old)->d_inode == ++ ovl_dentry_upper(new)->d_inode) ++ return 0; ++ } ++ ++ if (new_type != OVL_PATH_UPPER && ++ S_ISDIR(new->d_inode->i_mode)) { ++ err = ovl_check_empty_and_clear(new, new_type); ++ if (err) ++ return err; ++ } ++ } else { ++ new_type = OVL_PATH_UPPER; ++ } ++ ++ err = ovl_copy_up(old); ++ if (err) ++ return err; ++ ++ err = ovl_copy_up(new->d_parent); ++ if (err) ++ return err; ++ ++ old_upperdir = ovl_dentry_upper(old->d_parent); ++ new_upperdir = ovl_dentry_upper(new->d_parent); ++ ++ trap = lock_rename(new_upperdir, old_upperdir); ++ ++ olddentry = ovl_dentry_upper(old); ++ newdentry = ovl_dentry_upper(new); ++ if (newdentry) { ++ dget(newdentry); ++ } else { ++ new_create = true; ++ newdentry = ovl_lookup_create(new_upperdir, new); ++ err = PTR_ERR(newdentry); ++ if (IS_ERR(newdentry)) ++ goto out_unlock; ++ } ++ ++ err = -ESTALE; ++ if (olddentry->d_parent != old_upperdir) ++ goto out_dput; ++ if (newdentry->d_parent != new_upperdir) ++ goto out_dput; ++ if (olddentry == trap) ++ goto out_dput; ++ if (newdentry == trap) ++ goto out_dput; ++ ++ old_opaque = ovl_dentry_is_opaque(old); ++ new_opaque = ovl_dentry_is_opaque(new) || new_type != OVL_PATH_UPPER; ++ ++ if (is_dir && !old_opaque && new_opaque) { ++ err = ovl_set_opaque(olddentry); ++ if (err) ++ goto out_dput; ++ } ++ ++ err = vfs_rename(old_upperdir->d_inode, olddentry, ++ new_upperdir->d_inode, newdentry); ++ ++ if (err) { ++ if (new_create && ovl_dentry_is_opaque(new)) ++ ovl_whiteout(new_upperdir, new); ++ if (is_dir && !old_opaque && new_opaque) ++ ovl_remove_opaque(olddentry); ++ goto out_dput; ++ } ++ ++ if (old_type != OVL_PATH_UPPER || old_opaque) ++ err = ovl_whiteout(old_upperdir, old); ++ if (is_dir && old_opaque && !new_opaque) ++ ovl_remove_opaque(olddentry); ++ ++ if (old_opaque != new_opaque) ++ ovl_dentry_set_opaque(old, new_opaque); ++ ++ ovl_dentry_version_inc(old->d_parent); ++ ovl_dentry_version_inc(new->d_parent); ++ ++out_dput: ++ dput(newdentry); ++out_unlock: ++ unlock_rename(new_upperdir, old_upperdir); ++ return err; ++} ++ ++const struct inode_operations ovl_dir_inode_operations = { ++ .lookup = ovl_lookup, ++ .mkdir = ovl_mkdir, ++ .symlink = ovl_symlink, ++ .unlink = ovl_unlink, ++ .rmdir = ovl_rmdir, ++ .rename = ovl_rename, ++ .link = ovl_link, ++ .setattr = ovl_setattr, ++ .create = ovl_create, ++ .mknod = ovl_mknod, ++ .permission = ovl_permission, ++ .getattr = ovl_dir_getattr, ++ .setxattr = ovl_setxattr, ++ .getxattr = ovl_getxattr, ++ .listxattr = ovl_listxattr, ++ .removexattr = ovl_removexattr, ++}; +diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c +new file mode 100644 +index 0000000..ee37e92 +--- /dev/null ++++ b/fs/overlayfs/inode.c +@@ -0,0 +1,372 @@ ++/* ++ * ++ * Copyright (C) 2011 Novell Inc. ++ * ++ * This program is free software; you can redistribute it and/or modify it ++ * under the terms of the GNU General Public License version 2 as published by ++ * the Free Software Foundation. ++ */ ++ ++#include <linux/fs.h> ++#include <linux/slab.h> ++#include <linux/xattr.h> ++#include "overlayfs.h" ++ ++int ovl_setattr(struct dentry *dentry, struct iattr *attr) ++{ ++ struct dentry *upperdentry; ++ int err; ++ ++ if ((attr->ia_valid & ATTR_SIZE) && !ovl_dentry_upper(dentry)) ++ err = ovl_copy_up_truncate(dentry, attr->ia_size); ++ else ++ err = ovl_copy_up(dentry); ++ if (err) ++ return err; ++ ++ upperdentry = ovl_dentry_upper(dentry); ++ ++ if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) ++ attr->ia_valid &= ~ATTR_MODE; ++ ++ mutex_lock(&upperdentry->d_inode->i_mutex); ++ err = notify_change(upperdentry, attr); ++ if (!err) ++ ovl_copyattr(upperdentry->d_inode, dentry->d_inode); ++ mutex_unlock(&upperdentry->d_inode->i_mutex); ++ ++ return err; ++} ++ ++static int ovl_getattr(struct vfsmount *mnt, struct dentry *dentry, ++ struct kstat *stat) ++{ ++ struct path realpath; ++ ++ ovl_path_real(dentry, &realpath); ++ return vfs_getattr(&realpath, stat); ++} ++ ++int ovl_permission(struct inode *inode, int mask) ++{ ++ struct ovl_entry *oe; ++ struct dentry *alias = NULL; ++ struct inode *realinode; ++ struct dentry *realdentry; ++ bool is_upper; ++ int err; ++ ++ if (S_ISDIR(inode->i_mode)) { ++ oe = inode->i_private; ++ } else if (mask & MAY_NOT_BLOCK) { ++ return -ECHILD; ++ } else { ++ /* ++ * For non-directories find an alias and get the info ++ * from there. ++ */ ++ alias = d_find_any_alias(inode); ++ if (WARN_ON(!alias)) ++ return -ENOENT; ++ ++ oe = alias->d_fsdata; ++ } ++ ++ realdentry = ovl_entry_real(oe, &is_upper); ++ ++ /* Careful in RCU walk mode */ ++ realinode = ACCESS_ONCE(realdentry->d_inode); ++ if (!realinode) { ++ WARN_ON(!(mask & MAY_NOT_BLOCK)); ++ err = -ENOENT; ++ goto out_dput; ++ } ++ ++ if (mask & MAY_WRITE) { ++ umode_t mode = realinode->i_mode; ++ ++ /* ++ * Writes will always be redirected to upper layer, so ++ * ignore lower layer being read-only. ++ * ++ * If the overlay itself is read-only then proceed ++ * with the permission check, don't return EROFS. ++ * This will only happen if this is the lower layer of ++ * another overlayfs. ++ * ++ * If upper fs becomes read-only after the overlay was ++ * constructed return EROFS to prevent modification of ++ * upper layer. ++ */ ++ err = -EROFS; ++ if (is_upper && !IS_RDONLY(inode) && IS_RDONLY(realinode) && ++ (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) ++ goto out_dput; ++ } ++ ++ err = __inode_permission(realinode, mask); ++out_dput: ++ dput(alias); ++ return err; ++} ++ ++ ++struct ovl_link_data { ++ struct dentry *realdentry; ++ void *cookie; ++}; ++ ++static void *ovl_follow_link(struct dentry *dentry, struct nameidata *nd) ++{ ++ void *ret; ++ struct dentry *realdentry; ++ struct inode *realinode; ++ ++ realdentry = ovl_dentry_real(dentry); ++ realinode = realdentry->d_inode; ++ ++ if (WARN_ON(!realinode->i_op->follow_link)) ++ return ERR_PTR(-EPERM); ++ ++ ret = realinode->i_op->follow_link(realdentry, nd); ++ if (IS_ERR(ret)) ++ return ret; ++ ++ if (realinode->i_op->put_link) { ++ struct ovl_link_data *data; ++ ++ data = kmalloc(sizeof(struct ovl_link_data), GFP_KERNEL); ++ if (!data) { ++ realinode->i_op->put_link(realdentry, nd, ret); ++ return ERR_PTR(-ENOMEM); ++ } ++ data->realdentry = realdentry; ++ data->cookie = ret; ++ ++ return data; ++ } else { ++ return NULL; ++ } ++} ++ ++static void ovl_put_link(struct dentry *dentry, struct nameidata *nd, void *c) ++{ ++ struct inode *realinode; ++ struct ovl_link_data *data = c; ++ ++ if (!data) ++ return; ++ ++ realinode = data->realdentry->d_inode; ++ realinode->i_op->put_link(data->realdentry, nd, data->cookie); ++ kfree(data); ++} ++ ++static int ovl_readlink(struct dentry *dentry, char __user *buf, int bufsiz) ++{ ++ struct path realpath; ++ struct inode *realinode; ++ ++ ovl_path_real(dentry, &realpath); ++ realinode = realpath.dentry->d_inode; ++ ++ if (!realinode->i_op->readlink) ++ return -EINVAL; ++ ++ touch_atime(&realpath); ++ ++ return realinode->i_op->readlink(realpath.dentry, buf, bufsiz); ++} ++ ++ ++static bool ovl_is_private_xattr(const char *name) ++{ ++ return strncmp(name, "trusted.overlay.", 14) == 0; ++} ++ ++int ovl_setxattr(struct dentry *dentry, const char *name, ++ const void *value, size_t size, int flags) ++{ ++ int err; ++ struct dentry *upperdentry; ++ ++ if (ovl_is_private_xattr(name)) ++ return -EPERM; ++ ++ err = ovl_copy_up(dentry); ++ if (err) ++ return err; ++ ++ upperdentry = ovl_dentry_upper(dentry); ++ return vfs_setxattr(upperdentry, name, value, size, flags); ++} ++ ++ssize_t ovl_getxattr(struct dentry *dentry, const char *name, ++ void *value, size_t size) ++{ ++ if (ovl_path_type(dentry->d_parent) == OVL_PATH_MERGE && ++ ovl_is_private_xattr(name)) ++ return -ENODATA; ++ ++ return vfs_getxattr(ovl_dentry_real(dentry), name, value, size); ++} ++ ++ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) ++{ ++ ssize_t res; ++ int off; ++ ++ res = vfs_listxattr(ovl_dentry_real(dentry), list, size); ++ if (res <= 0 || size == 0) ++ return res; ++ ++ if (ovl_path_type(dentry->d_parent) != OVL_PATH_MERGE) ++ return res; ++ ++ /* filter out private xattrs */ ++ for (off = 0; off < res;) { ++ char *s = list + off; ++ size_t slen = strlen(s) + 1; ++ ++ BUG_ON(off + slen > res); ++ ++ if (ovl_is_private_xattr(s)) { ++ res -= slen; ++ memmove(s, s + slen, res - off); ++ } else { ++ off += slen; ++ } ++ } ++ ++ return res; ++} ++ ++int ovl_removexattr(struct dentry *dentry, const char *name) ++{ ++ int err; ++ struct path realpath; ++ enum ovl_path_type type; ++ ++ if (ovl_path_type(dentry->d_parent) == OVL_PATH_MERGE && ++ ovl_is_private_xattr(name)) ++ return -ENODATA; ++ ++ type = ovl_path_real(dentry, &realpath); ++ if (type == OVL_PATH_LOWER) { ++ err = vfs_getxattr(realpath.dentry, name, NULL, 0); ++ if (err < 0) ++ return err; ++ ++ err = ovl_copy_up(dentry); ++ if (err) ++ return err; ++ ++ ovl_path_upper(dentry, &realpath); ++ } ++ ++ return vfs_removexattr(realpath.dentry, name); ++} ++ ++static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type, ++ struct dentry *realdentry) ++{ ++ if (type != OVL_PATH_LOWER) ++ return false; ++ ++ if (special_file(realdentry->d_inode->i_mode)) ++ return false; ++ ++ if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC)) ++ return false; ++ ++ return true; ++} ++ ++static int ovl_dentry_open(struct dentry *dentry, struct file *file, ++ const struct cred *cred) ++{ ++ int err; ++ struct path realpath; ++ enum ovl_path_type type; ++ ++ type = ovl_path_real(dentry, &realpath); ++ if (ovl_open_need_copy_up(file->f_flags, type, realpath.dentry)) { ++ if (file->f_flags & O_TRUNC) ++ err = ovl_copy_up_truncate(dentry, 0); ++ else ++ err = ovl_copy_up(dentry); ++ if (err) ++ return err; ++ ++ ovl_path_upper(dentry, &realpath); ++ } ++ ++ return vfs_open(&realpath, file, cred); ++} ++ ++static const struct inode_operations ovl_file_inode_operations = { ++ .setattr = ovl_setattr, ++ .permission = ovl_permission, ++ .getattr = ovl_getattr, ++ .setxattr = ovl_setxattr, ++ .getxattr = ovl_getxattr, ++ .listxattr = ovl_listxattr, ++ .removexattr = ovl_removexattr, ++ .dentry_open = ovl_dentry_open, ++}; ++ ++static const struct inode_operations ovl_symlink_inode_operations = { ++ .setattr = ovl_setattr, ++ .follow_link = ovl_follow_link, ++ .put_link = ovl_put_link, ++ .readlink = ovl_readlink, ++ .getattr = ovl_getattr, ++ .setxattr = ovl_setxattr, ++ .getxattr = ovl_getxattr, ++ .listxattr = ovl_listxattr, ++ .removexattr = ovl_removexattr, ++}; ++ ++struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, ++ struct ovl_entry *oe) ++{ ++ struct inode *inode; ++ ++ inode = new_inode(sb); ++ if (!inode) ++ return NULL; ++ ++ mode &= S_IFMT; ++ ++ inode->i_ino = get_next_ino(); ++ inode->i_mode = mode; ++ inode->i_flags |= S_NOATIME | S_NOCMTIME; ++ ++ switch (mode) { ++ case S_IFDIR: ++ inode->i_private = oe; ++ inode->i_op = &ovl_dir_inode_operations; ++ inode->i_fop = &ovl_dir_operations; ++ break; ++ ++ case S_IFLNK: ++ inode->i_op = &ovl_symlink_inode_operations; ++ break; ++ ++ case S_IFREG: ++ case S_IFSOCK: ++ case S_IFBLK: ++ case S_IFCHR: ++ case S_IFIFO: ++ inode->i_op = &ovl_file_inode_operations; ++ break; ++ ++ default: ++ WARN(1, "illegal file type: %i\n", mode); ++ iput(inode); ++ inode = NULL; ++ } ++ ++ return inode; ++ ++} +diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h +new file mode 100644 +index 0000000..1cba38f +--- /dev/null ++++ b/fs/overlayfs/overlayfs.h +@@ -0,0 +1,70 @@ ++/* ++ * ++ * Copyright (C) 2011 Novell Inc. ++ * ++ * This program is free software; you can redistribute it and/or modify it ++ * under the terms of the GNU General Public License version 2 as published by ++ * the Free Software Foundation. ++ */ ++ ++struct ovl_entry; ++ ++enum ovl_path_type { ++ OVL_PATH_UPPER, ++ OVL_PATH_MERGE, ++ OVL_PATH_LOWER, ++}; ++ ++extern const char *ovl_opaque_xattr; ++extern const char *ovl_whiteout_xattr; ++extern const struct dentry_operations ovl_dentry_operations; ++ ++enum ovl_path_type ovl_path_type(struct dentry *dentry); ++u64 ovl_dentry_version_get(struct dentry *dentry); ++void ovl_dentry_version_inc(struct dentry *dentry); ++void ovl_path_upper(struct dentry *dentry, struct path *path); ++void ovl_path_lower(struct dentry *dentry, struct path *path); ++enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path); ++struct dentry *ovl_dentry_upper(struct dentry *dentry); ++struct dentry *ovl_dentry_lower(struct dentry *dentry); ++struct dentry *ovl_dentry_real(struct dentry *dentry); ++struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper); ++bool ovl_dentry_is_opaque(struct dentry *dentry); ++void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque); ++bool ovl_is_whiteout(struct dentry *dentry); ++void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry); ++struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, ++ unsigned int flags); ++struct file *ovl_path_open(struct path *path, int flags); ++ ++struct dentry *ovl_upper_create(struct dentry *upperdir, struct dentry *dentry, ++ struct kstat *stat, const char *link); ++ ++/* readdir.c */ ++extern const struct file_operations ovl_dir_operations; ++int ovl_check_empty_and_clear(struct dentry *dentry, enum ovl_path_type type); ++ ++/* inode.c */ ++int ovl_setattr(struct dentry *dentry, struct iattr *attr); ++int ovl_permission(struct inode *inode, int mask); ++int ovl_setxattr(struct dentry *dentry, const char *name, ++ const void *value, size_t size, int flags); ++ssize_t ovl_getxattr(struct dentry *dentry, const char *name, ++ void *value, size_t size); ++ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size); ++int ovl_removexattr(struct dentry *dentry, const char *name); ++ ++struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, ++ struct ovl_entry *oe); ++static inline void ovl_copyattr(struct inode *from, struct inode *to) ++{ ++ to->i_uid = from->i_uid; ++ to->i_gid = from->i_gid; ++} ++ ++/* dir.c */ ++extern const struct inode_operations ovl_dir_inode_operations; ++ ++/* copy_up.c */ ++int ovl_copy_up(struct dentry *dentry); ++int ovl_copy_up_truncate(struct dentry *dentry, loff_t size); +diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c +new file mode 100644 +index 0000000..0797efb +--- /dev/null ++++ b/fs/overlayfs/readdir.c +@@ -0,0 +1,566 @@ ++/* ++ * ++ * Copyright (C) 2011 Novell Inc. ++ * ++ * This program is free software; you can redistribute it and/or modify it ++ * under the terms of the GNU General Public License version 2 as published by ++ * the Free Software Foundation. ++ */ ++ ++#include <linux/fs.h> ++#include <linux/slab.h> ++#include <linux/namei.h> ++#include <linux/file.h> ++#include <linux/xattr.h> ++#include <linux/rbtree.h> ++#include <linux/security.h> ++#include <linux/cred.h> ++#include "overlayfs.h" ++ ++struct ovl_cache_entry { ++ const char *name; ++ unsigned int len; ++ unsigned int type; ++ u64 ino; ++ bool is_whiteout; ++ struct list_head l_node; ++ struct rb_node node; ++}; ++ ++struct ovl_readdir_data { ++ struct rb_root *root; ++ struct list_head *list; ++ struct list_head *middle; ++ struct dentry *dir; ++ int count; ++ int err; ++}; ++ ++struct ovl_dir_file { ++ bool is_real; ++ bool is_cached; ++ struct list_head cursor; ++ u64 cache_version; ++ struct list_head cache; ++ struct file *realfile; ++}; ++ ++static struct ovl_cache_entry *ovl_cache_entry_from_node(struct rb_node *n) ++{ ++ return container_of(n, struct ovl_cache_entry, node); ++} ++ ++static struct ovl_cache_entry *ovl_cache_entry_find(struct rb_root *root, ++ const char *name, int len) ++{ ++ struct rb_node *node = root->rb_node; ++ int cmp; ++ ++ while (node) { ++ struct ovl_cache_entry *p = ovl_cache_entry_from_node(node); ++ ++ cmp = strncmp(name, p->name, len); ++ if (cmp > 0) ++ node = p->node.rb_right; ++ else if (cmp < 0 || len < p->len) ++ node = p->node.rb_left; ++ else ++ return p; ++ } ++ ++ return NULL; ++} ++ ++static struct ovl_cache_entry *ovl_cache_entry_new(const char *name, int len, ++ u64 ino, unsigned int d_type) ++{ ++ struct ovl_cache_entry *p; ++ ++ p = kmalloc(sizeof(*p) + len + 1, GFP_KERNEL); ++ if (p) { ++ char *name_copy = (char *) (p + 1); ++ memcpy(name_copy, name, len); ++ name_copy[len] = '\0'; ++ p->name = name_copy; ++ p->len = len; ++ p->type = d_type; ++ p->ino = ino; ++ p->is_whiteout = false; ++ } ++ ++ return p; ++} ++ ++static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd, ++ const char *name, int len, u64 ino, ++ unsigned int d_type) ++{ ++ struct rb_node **newp = &rdd->root->rb_node; ++ struct rb_node *parent = NULL; ++ struct ovl_cache_entry *p; ++ ++ while (*newp) { ++ int cmp; ++ struct ovl_cache_entry *tmp; ++ ++ parent = *newp; ++ tmp = ovl_cache_entry_from_node(*newp); ++ cmp = strncmp(name, tmp->name, len); ++ if (cmp > 0) ++ newp = &tmp->node.rb_right; ++ else if (cmp < 0 || len < tmp->len) ++ newp = &tmp->node.rb_left; ++ else ++ return 0; ++ } ++ ++ p = ovl_cache_entry_new(name, len, ino, d_type); ++ if (p == NULL) ++ return -ENOMEM; ++ ++ list_add_tail(&p->l_node, rdd->list); ++ rb_link_node(&p->node, parent, newp); ++ rb_insert_color(&p->node, rdd->root); ++ ++ return 0; ++} ++ ++static int ovl_fill_lower(void *buf, const char *name, int namelen, ++ loff_t offset, u64 ino, unsigned int d_type) ++{ ++ struct ovl_readdir_data *rdd = buf; ++ struct ovl_cache_entry *p; ++ ++ rdd->count++; ++ p = ovl_cache_entry_find(rdd->root, name, namelen); ++ if (p) { ++ list_move_tail(&p->l_node, rdd->middle); ++ } else { ++ p = ovl_cache_entry_new(name, namelen, ino, d_type); ++ if (p == NULL) ++ rdd->err = -ENOMEM; ++ else ++ list_add_tail(&p->l_node, rdd->middle); ++ } ++ ++ return rdd->err; ++} ++ ++static void ovl_cache_free(struct list_head *list) ++{ ++ struct ovl_cache_entry *p; ++ struct ovl_cache_entry *n; ++ ++ list_for_each_entry_safe(p, n, list, l_node) ++ kfree(p); ++ ++ INIT_LIST_HEAD(list); ++} ++ ++static int ovl_fill_upper(void *buf, const char *name, int namelen, ++ loff_t offset, u64 ino, unsigned int d_type) ++{ ++ struct ovl_readdir_data *rdd = buf; ++ ++ rdd->count++; ++ return ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_type); ++} ++ ++static inline int ovl_dir_read(struct path *realpath, ++ struct ovl_readdir_data *rdd, filldir_t filler) ++{ ++ struct file *realfile; ++ int err; ++ ++ realfile = ovl_path_open(realpath, O_RDONLY | O_DIRECTORY); ++ if (IS_ERR(realfile)) ++ return PTR_ERR(realfile); ++ ++ do { ++ rdd->count = 0; ++ rdd->err = 0; ++ err = vfs_readdir(realfile, filler, rdd); ++ if (err >= 0) ++ err = rdd->err; ++ } while (!err && rdd->count); ++ fput(realfile); ++ ++ return 0; ++} ++ ++static void ovl_dir_reset(struct file *file) ++{ ++ struct ovl_dir_file *od = file->private_data; ++ enum ovl_path_type type = ovl_path_type(file->f_path.dentry); ++ ++ if (ovl_dentry_version_get(file->f_path.dentry) != od->cache_version) { ++ list_del_init(&od->cursor); ++ ovl_cache_free(&od->cache); ++ od->is_cached = false; ++ } ++ WARN_ON(!od->is_real && type != OVL_PATH_MERGE); ++ if (od->is_real && type == OVL_PATH_MERGE) { ++ fput(od->realfile); ++ od->realfile = NULL; ++ od->is_real = false; ++ } ++} ++ ++static int ovl_dir_mark_whiteouts(struct ovl_readdir_data *rdd) ++{ ++ struct ovl_cache_entry *p; ++ struct dentry *dentry; ++ const struct cred *old_cred; ++ struct cred *override_cred; ++ ++ override_cred = prepare_creds(); ++ if (!override_cred) { ++ ovl_cache_free(rdd->list); ++ return -ENOMEM; ++ } ++ ++ /* ++ * CAP_SYS_ADMIN for getxattr ++ * CAP_DAC_OVERRIDE for lookup ++ */ ++ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); ++ cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); ++ old_cred = override_creds(override_cred); ++ ++ mutex_lock(&rdd->dir->d_inode->i_mutex); ++ list_for_each_entry(p, rdd->list, l_node) { ++ if (p->type != DT_LNK) ++ continue; ++ ++ dentry = lookup_one_len(p->name, rdd->dir, p->len); ++ if (IS_ERR(dentry)) ++ continue; ++ ++ p->is_whiteout = ovl_is_whiteout(dentry); ++ dput(dentry); ++ } ++ mutex_unlock(&rdd->dir->d_inode->i_mutex); ++ ++ revert_creds(old_cred); ++ put_cred(override_cred); ++ ++ return 0; ++} ++ ++static inline int ovl_dir_read_merged(struct path *upperpath, ++ struct path *lowerpath, ++ struct ovl_readdir_data *rdd) ++{ ++ int err; ++ struct rb_root root = RB_ROOT; ++ struct list_head middle; ++ ++ rdd->root = &root; ++ if (upperpath->dentry) { ++ rdd->dir = upperpath->dentry; ++ err = ovl_dir_read(upperpath, rdd, ovl_fill_upper); ++ if (err) ++ goto out; ++ ++ err = ovl_dir_mark_whiteouts(rdd); ++ if (err) ++ goto out; ++ } ++ /* ++ * Insert lowerpath entries before upperpath ones, this allows ++ * offsets to be reasonably constant ++ */ ++ list_add(&middle, rdd->list); ++ rdd->middle = &middle; ++ err = ovl_dir_read(lowerpath, rdd, ovl_fill_lower); ++ list_del(&middle); ++out: ++ rdd->root = NULL; ++ ++ return err; ++} ++ ++static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos) ++{ ++ struct list_head *l; ++ loff_t off; ++ ++ l = od->cache.next; ++ for (off = 0; off < pos; off++) { ++ if (l == &od->cache) ++ break; ++ l = l->next; ++ } ++ list_move_tail(&od->cursor, l); ++} ++ ++static int ovl_readdir(struct file *file, void *buf, filldir_t filler) ++{ ++ struct ovl_dir_file *od = file->private_data; ++ int res; ++ ++ if (!file->f_pos) ++ ovl_dir_reset(file); ++ ++ if (od->is_real) { ++ res = vfs_readdir(od->realfile, filler, buf); ++ file->f_pos = od->realfile->f_pos; ++ ++ return res; ++ } ++ ++ if (!od->is_cached) { ++ struct path lowerpath; ++ struct path upperpath; ++ struct ovl_readdir_data rdd = { .list = &od->cache }; ++ ++ ovl_path_lower(file->f_path.dentry, &lowerpath); ++ ovl_path_upper(file->f_path.dentry, &upperpath); ++ ++ res = ovl_dir_read_merged(&upperpath, &lowerpath, &rdd); ++ if (res) { ++ ovl_cache_free(rdd.list); ++ return res; ++ } ++ ++ od->cache_version = ovl_dentry_version_get(file->f_path.dentry); ++ od->is_cached = true; ++ ++ ovl_seek_cursor(od, file->f_pos); ++ } ++ ++ while (od->cursor.next != &od->cache) { ++ int over; ++ loff_t off; ++ struct ovl_cache_entry *p; ++ ++ p = list_entry(od->cursor.next, struct ovl_cache_entry, l_node); ++ off = file->f_pos; ++ if (!p->is_whiteout) { ++ over = filler(buf, p->name, p->len, off, p->ino, ++ p->type); ++ if (over) ++ break; ++ } ++ file->f_pos++; ++ list_move(&od->cursor, &p->l_node); ++ } ++ ++ return 0; ++} ++ ++static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin) ++{ ++ loff_t res; ++ struct ovl_dir_file *od = file->private_data; ++ ++ mutex_lock(&file->f_dentry->d_inode->i_mutex); ++ if (!file->f_pos) ++ ovl_dir_reset(file); ++ ++ if (od->is_real) { ++ res = vfs_llseek(od->realfile, offset, origin); ++ file->f_pos = od->realfile->f_pos; ++ } else { ++ res = -EINVAL; ++ ++ switch (origin) { ++ case SEEK_CUR: ++ offset += file->f_pos; ++ break; ++ case SEEK_SET: ++ break; ++ default: ++ goto out_unlock; ++ } ++ if (offset < 0) ++ goto out_unlock; ++ ++ if (offset != file->f_pos) { ++ file->f_pos = offset; ++ if (od->is_cached) ++ ovl_seek_cursor(od, offset); ++ } ++ res = offset; ++ } ++out_unlock: ++ mutex_unlock(&file->f_dentry->d_inode->i_mutex); ++ ++ return res; ++} ++ ++static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end, ++ int datasync) ++{ ++ struct ovl_dir_file *od = file->private_data; ++ ++ /* May need to reopen directory if it got copied up */ ++ if (!od->realfile) { ++ struct path upperpath; ++ ++ ovl_path_upper(file->f_path.dentry, &upperpath); ++ od->realfile = ovl_path_open(&upperpath, O_RDONLY); ++ if (IS_ERR(od->realfile)) ++ return PTR_ERR(od->realfile); ++ } ++ ++ return vfs_fsync_range(od->realfile, start, end, datasync); ++} ++ ++static int ovl_dir_release(struct inode *inode, struct file *file) ++{ ++ struct ovl_dir_file *od = file->private_data; ++ ++ list_del(&od->cursor); ++ ovl_cache_free(&od->cache); ++ if (od->realfile) ++ fput(od->realfile); ++ kfree(od); ++ ++ return 0; ++} ++ ++static int ovl_dir_open(struct inode *inode, struct file *file) ++{ ++ struct path realpath; ++ struct file *realfile; ++ struct ovl_dir_file *od; ++ enum ovl_path_type type; ++ ++ od = kzalloc(sizeof(struct ovl_dir_file), GFP_KERNEL); ++ if (!od) ++ return -ENOMEM; ++ ++ type = ovl_path_real(file->f_path.dentry, &realpath); ++ realfile = ovl_path_open(&realpath, file->f_flags); ++ if (IS_ERR(realfile)) { ++ kfree(od); ++ return PTR_ERR(realfile); ++ } ++ INIT_LIST_HEAD(&od->cache); ++ INIT_LIST_HEAD(&od->cursor); ++ od->is_cached = false; ++ od->realfile = realfile; ++ od->is_real = (type != OVL_PATH_MERGE); ++ file->private_data = od; ++ ++ return 0; ++} ++ ++const struct file_operations ovl_dir_operations = { ++ .read = generic_read_dir, ++ .open = ovl_dir_open, ++ .readdir = ovl_readdir, ++ .llseek = ovl_dir_llseek, ++ .fsync = ovl_dir_fsync, ++ .release = ovl_dir_release, ++}; ++ ++static int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list) ++{ ++ int err; ++ struct path lowerpath; ++ struct path upperpath; ++ struct ovl_cache_entry *p; ++ struct ovl_readdir_data rdd = { .list = list }; ++ ++ ovl_path_upper(dentry, &upperpath); ++ ovl_path_lower(dentry, &lowerpath); ++ ++ err = ovl_dir_read_merged(&upperpath, &lowerpath, &rdd); ++ if (err) ++ return err; ++ ++ err = 0; ++ ++ list_for_each_entry(p, list, l_node) { ++ if (p->is_whiteout) ++ continue; ++ ++ if (p->name[0] == '.') { ++ if (p->len == 1) ++ continue; ++ if (p->len == 2 && p->name[1] == '.') ++ continue; ++ } ++ err = -ENOTEMPTY; ++ break; ++ } ++ ++ return err; ++} ++ ++static int ovl_remove_whiteouts(struct dentry *dir, struct list_head *list) ++{ ++ struct path upperpath; ++ struct dentry *upperdir; ++ struct ovl_cache_entry *p; ++ const struct cred *old_cred; ++ struct cred *override_cred; ++ int err; ++ ++ ovl_path_upper(dir, &upperpath); ++ upperdir = upperpath.dentry; ++ ++ override_cred = prepare_creds(); ++ if (!override_cred) ++ return -ENOMEM; ++ ++ /* ++ * CAP_DAC_OVERRIDE for lookup and unlink ++ * CAP_SYS_ADMIN for setxattr of "trusted" namespace ++ * CAP_FOWNER for unlink in sticky directory ++ */ ++ cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); ++ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); ++ cap_raise(override_cred->cap_effective, CAP_FOWNER); ++ old_cred = override_creds(override_cred); ++ ++ err = vfs_setxattr(upperdir, ovl_opaque_xattr, "y", 1, 0); ++ if (err) ++ goto out_revert_creds; ++ ++ mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT); ++ list_for_each_entry(p, list, l_node) { ++ struct dentry *dentry; ++ int ret; ++ ++ if (!p->is_whiteout) ++ continue; ++ ++ dentry = lookup_one_len(p->name, upperdir, p->len); ++ if (IS_ERR(dentry)) { ++ printk(KERN_WARNING ++ "overlayfs: failed to lookup whiteout %.*s: %li\n", ++ p->len, p->name, PTR_ERR(dentry)); ++ continue; ++ } ++ ret = vfs_unlink(upperdir->d_inode, dentry); ++ dput(dentry); ++ if (ret) ++ printk(KERN_WARNING ++ "overlayfs: failed to unlink whiteout %.*s: %i\n", ++ p->len, p->name, ret); ++ } ++ mutex_unlock(&upperdir->d_inode->i_mutex); ++ ++out_revert_creds: ++ revert_creds(old_cred); ++ put_cred(override_cred); ++ ++ return err; ++} ++ ++int ovl_check_empty_and_clear(struct dentry *dentry, enum ovl_path_type type) ++{ ++ int err; ++ LIST_HEAD(list); ++ ++ err = ovl_check_empty_dir(dentry, &list); ++ if (!err && type == OVL_PATH_MERGE) ++ err = ovl_remove_whiteouts(dentry, &list); ++ ++ ovl_cache_free(&list); ++ ++ return err; ++} +diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c +new file mode 100644 +index 0000000..357d6e8 +--- /dev/null ++++ b/fs/overlayfs/super.c +@@ -0,0 +1,685 @@ ++/* ++ * ++ * Copyright (C) 2011 Novell Inc. ++ * ++ * This program is free software; you can redistribute it and/or modify it ++ * under the terms of the GNU General Public License version 2 as published by ++ * the Free Software Foundation. ++ */ ++ ++#include <linux/fs.h> ++#include <linux/namei.h> ++#include <linux/xattr.h> ++#include <linux/security.h> ++#include <linux/mount.h> ++#include <linux/slab.h> ++#include <linux/parser.h> ++#include <linux/module.h> ++#include <linux/cred.h> ++#include <linux/sched.h> ++#include <linux/statfs.h> ++#include <linux/seq_file.h> ++#include "overlayfs.h" ++ ++MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>"); ++MODULE_DESCRIPTION("Overlay filesystem"); ++MODULE_LICENSE("GPL"); ++ ++#define OVERLAYFS_SUPER_MAGIC 0x794c764f ++ ++struct ovl_config { ++ char *lowerdir; ++ char *upperdir; ++}; ++ ++/* private information held for overlayfs's superblock */ ++struct ovl_fs { ++ struct vfsmount *upper_mnt; ++ struct vfsmount *lower_mnt; ++ long lower_namelen; ++ /* pathnames of lower and upper dirs, for show_options */ ++ struct ovl_config config; ++}; ++ ++/* private information held for every overlayfs dentry */ ++struct ovl_entry { ++ /* ++ * Keep "double reference" on upper dentries, so that ++ * d_delete() doesn't think it's OK to reset d_inode to NULL. ++ */ ++ struct dentry *__upperdentry; ++ struct dentry *lowerdentry; ++ union { ++ struct { ++ u64 version; ++ bool opaque; ++ }; ++ struct rcu_head rcu; ++ }; ++}; ++ ++const char *ovl_whiteout_xattr = "trusted.overlay.whiteout"; ++const char *ovl_opaque_xattr = "trusted.overlay.opaque"; ++ ++ ++enum ovl_path_type ovl_path_type(struct dentry *dentry) ++{ ++ struct ovl_entry *oe = dentry->d_fsdata; ++ ++ if (oe->__upperdentry) { ++ if (oe->lowerdentry && S_ISDIR(dentry->d_inode->i_mode)) ++ return OVL_PATH_MERGE; ++ else ++ return OVL_PATH_UPPER; ++ } else { ++ return OVL_PATH_LOWER; ++ } ++} ++ ++static struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe) ++{ ++ struct dentry *upperdentry = ACCESS_ONCE(oe->__upperdentry); ++ smp_read_barrier_depends(); ++ return upperdentry; ++} ++ ++void ovl_path_upper(struct dentry *dentry, struct path *path) ++{ ++ struct ovl_fs *ofs = dentry->d_sb->s_fs_info; ++ struct ovl_entry *oe = dentry->d_fsdata; ++ ++ path->mnt = ofs->upper_mnt; ++ path->dentry = ovl_upperdentry_dereference(oe); ++} ++ ++void ovl_path_lower(struct dentry *dentry, struct path *path) ++{ ++ struct ovl_fs *ofs = dentry->d_sb->s_fs_info; ++ struct ovl_entry *oe = dentry->d_fsdata; ++ ++ path->mnt = ofs->lower_mnt; ++ path->dentry = oe->lowerdentry; ++} ++ ++enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path) ++{ ++ ++ enum ovl_path_type type = ovl_path_type(dentry); ++ ++ if (type == OVL_PATH_LOWER) ++ ovl_path_lower(dentry, path); ++ else ++ ovl_path_upper(dentry, path); ++ ++ return type; ++} ++ ++struct dentry *ovl_dentry_upper(struct dentry *dentry) ++{ ++ struct ovl_entry *oe = dentry->d_fsdata; ++ ++ return ovl_upperdentry_dereference(oe); ++} ++ ++struct dentry *ovl_dentry_lower(struct dentry *dentry) ++{ ++ struct ovl_entry *oe = dentry->d_fsdata; ++ ++ return oe->lowerdentry; ++} ++ ++struct dentry *ovl_dentry_real(struct dentry *dentry) ++{ ++ struct ovl_entry *oe = dentry->d_fsdata; ++ struct dentry *realdentry; ++ ++ realdentry = ovl_upperdentry_dereference(oe); ++ if (!realdentry) ++ realdentry = oe->lowerdentry; ++ ++ return realdentry; ++} ++ ++struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper) ++{ ++ struct dentry *realdentry; ++ ++ realdentry = ovl_upperdentry_dereference(oe); ++ if (realdentry) { ++ *is_upper = true; ++ } else { ++ realdentry = oe->lowerdentry; ++ *is_upper = false; ++ } ++ return realdentry; ++} ++ ++bool ovl_dentry_is_opaque(struct dentry *dentry) ++{ ++ struct ovl_entry *oe = dentry->d_fsdata; ++ return oe->opaque; ++} ++ ++void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque) ++{ ++ struct ovl_entry *oe = dentry->d_fsdata; ++ oe->opaque = opaque; ++} ++ ++void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry) ++{ ++ struct ovl_entry *oe = dentry->d_fsdata; ++ ++ WARN_ON(!mutex_is_locked(&upperdentry->d_parent->d_inode->i_mutex)); ++ WARN_ON(oe->__upperdentry); ++ BUG_ON(!upperdentry->d_inode); ++ smp_wmb(); ++ oe->__upperdentry = dget(upperdentry); ++} ++ ++void ovl_dentry_version_inc(struct dentry *dentry) ++{ ++ struct ovl_entry *oe = dentry->d_fsdata; ++ ++ WARN_ON(!mutex_is_locked(&dentry->d_inode->i_mutex)); ++ oe->version++; ++} ++ ++u64 ovl_dentry_version_get(struct dentry *dentry) ++{ ++ struct ovl_entry *oe = dentry->d_fsdata; ++ ++ WARN_ON(!mutex_is_locked(&dentry->d_inode->i_mutex)); ++ return oe->version; ++} ++ ++bool ovl_is_whiteout(struct dentry *dentry) ++{ ++ int res; ++ char val; ++ ++ if (!dentry) ++ return false; ++ if (!dentry->d_inode) ++ return false; ++ if (!S_ISLNK(dentry->d_inode->i_mode)) ++ return false; ++ ++ res = vfs_getxattr(dentry, ovl_whiteout_xattr, &val, 1); ++ if (res == 1 && val == 'y') ++ return true; ++ ++ return false; ++} ++ ++static bool ovl_is_opaquedir(struct dentry *dentry) ++{ ++ int res; ++ char val; ++ ++ if (!S_ISDIR(dentry->d_inode->i_mode)) ++ return false; ++ ++ res = vfs_getxattr(dentry, ovl_opaque_xattr, &val, 1); ++ if (res == 1 && val == 'y') ++ return true; ++ ++ return false; ++} ++ ++static void ovl_entry_free(struct rcu_head *head) ++{ ++ struct ovl_entry *oe = container_of(head, struct ovl_entry, rcu); ++ kfree(oe); ++} ++ ++static void ovl_dentry_release(struct dentry *dentry) ++{ ++ struct ovl_entry *oe = dentry->d_fsdata; ++ ++ if (oe) { ++ dput(oe->__upperdentry); ++ dput(oe->__upperdentry); ++ dput(oe->lowerdentry); ++ call_rcu(&oe->rcu, ovl_entry_free); ++ } ++} ++ ++const struct dentry_operations ovl_dentry_operations = { ++ .d_release = ovl_dentry_release, ++}; ++ ++static struct ovl_entry *ovl_alloc_entry(void) ++{ ++ return kzalloc(sizeof(struct ovl_entry), GFP_KERNEL); ++} ++ ++static inline struct dentry *ovl_lookup_real(struct dentry *dir, ++ struct qstr *name) ++{ ++ struct dentry *dentry; ++ ++ mutex_lock(&dir->d_inode->i_mutex); ++ dentry = lookup_one_len(name->name, dir, name->len); ++ mutex_unlock(&dir->d_inode->i_mutex); ++ ++ if (IS_ERR(dentry)) { ++ if (PTR_ERR(dentry) == -ENOENT) ++ dentry = NULL; ++ } else if (!dentry->d_inode) { ++ dput(dentry); ++ dentry = NULL; ++ } ++ return dentry; ++} ++ ++static int ovl_do_lookup(struct dentry *dentry) ++{ ++ struct ovl_entry *oe; ++ struct dentry *upperdir; ++ struct dentry *lowerdir; ++ struct dentry *upperdentry = NULL; ++ struct dentry *lowerdentry = NULL; ++ struct inode *inode = NULL; ++ int err; ++ ++ err = -ENOMEM; ++ oe = ovl_alloc_entry(); ++ if (!oe) ++ goto out; ++ ++ upperdir = ovl_dentry_upper(dentry->d_parent); ++ lowerdir = ovl_dentry_lower(dentry->d_parent); ++ ++ if (upperdir) { ++ upperdentry = ovl_lookup_real(upperdir, &dentry->d_name); ++ err = PTR_ERR(upperdentry); ++ if (IS_ERR(upperdentry)) ++ goto out_put_dir; ++ ++ if (lowerdir && upperdentry && ++ (S_ISLNK(upperdentry->d_inode->i_mode) || ++ S_ISDIR(upperdentry->d_inode->i_mode))) { ++ const struct cred *old_cred; ++ struct cred *override_cred; ++ ++ err = -ENOMEM; ++ override_cred = prepare_creds(); ++ if (!override_cred) ++ goto out_dput_upper; ++ ++ /* CAP_SYS_ADMIN needed for getxattr */ ++ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); ++ old_cred = override_creds(override_cred); ++ ++ if (ovl_is_opaquedir(upperdentry)) { ++ oe->opaque = true; ++ } else if (ovl_is_whiteout(upperdentry)) { ++ dput(upperdentry); ++ upperdentry = NULL; ++ oe->opaque = true; ++ } ++ revert_creds(old_cred); ++ put_cred(override_cred); ++ } ++ } ++ if (lowerdir && !oe->opaque) { ++ lowerdentry = ovl_lookup_real(lowerdir, &dentry->d_name); ++ err = PTR_ERR(lowerdentry); ++ if (IS_ERR(lowerdentry)) ++ goto out_dput_upper; ++ } ++ ++ if (lowerdentry && upperdentry && ++ (!S_ISDIR(upperdentry->d_inode->i_mode) || ++ !S_ISDIR(lowerdentry->d_inode->i_mode))) { ++ dput(lowerdentry); ++ lowerdentry = NULL; ++ oe->opaque = true; ++ } ++ ++ if (lowerdentry || upperdentry) { ++ struct dentry *realdentry; ++ ++ realdentry = upperdentry ? upperdentry : lowerdentry; ++ err = -ENOMEM; ++ inode = ovl_new_inode(dentry->d_sb, realdentry->d_inode->i_mode, ++ oe); ++ if (!inode) ++ goto out_dput; ++ ovl_copyattr(realdentry->d_inode, inode); ++ } ++ ++ if (upperdentry) ++ oe->__upperdentry = dget(upperdentry); ++ ++ if (lowerdentry) ++ oe->lowerdentry = lowerdentry; ++ ++ dentry->d_fsdata = oe; ++ dentry->d_op = &ovl_dentry_operations; ++ d_add(dentry, inode); ++ ++ return 0; ++ ++out_dput: ++ dput(lowerdentry); ++out_dput_upper: ++ dput(upperdentry); ++out_put_dir: ++ kfree(oe); ++out: ++ return err; ++} ++ ++struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, ++ unsigned int flags) ++{ ++ int err = ovl_do_lookup(dentry); ++ ++ if (err) ++ return ERR_PTR(err); ++ ++ return NULL; ++} ++ ++struct file *ovl_path_open(struct path *path, int flags) ++{ ++ path_get(path); ++ return dentry_open(path, flags, current_cred()); ++} ++ ++static void ovl_put_super(struct super_block *sb) ++{ ++ struct ovl_fs *ufs = sb->s_fs_info; ++ ++ if (!(sb->s_flags & MS_RDONLY)) ++ mnt_drop_write(ufs->upper_mnt); ++ ++ mntput(ufs->upper_mnt); ++ mntput(ufs->lower_mnt); ++ ++ kfree(ufs->config.lowerdir); ++ kfree(ufs->config.upperdir); ++ kfree(ufs); ++} ++ ++static int ovl_remount_fs(struct super_block *sb, int *flagsp, char *data) ++{ ++ int flags = *flagsp; ++ struct ovl_fs *ufs = sb->s_fs_info; ++ ++ /* When remounting rw or ro, we need to adjust the write access to the ++ * upper fs. ++ */ ++ if (((flags ^ sb->s_flags) & MS_RDONLY) == 0) ++ /* No change to readonly status */ ++ return 0; ++ ++ if (flags & MS_RDONLY) { ++ mnt_drop_write(ufs->upper_mnt); ++ return 0; ++ } else ++ return mnt_want_write(ufs->upper_mnt); ++} ++ ++/** ++ * ovl_statfs ++ * @sb: The overlayfs super block ++ * @buf: The struct kstatfs to fill in with stats ++ * ++ * Get the filesystem statistics. As writes always target the upper layer ++ * filesystem pass the statfs to the same filesystem. ++ */ ++static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf) ++{ ++ struct ovl_fs *ofs = dentry->d_sb->s_fs_info; ++ struct dentry *root_dentry = dentry->d_sb->s_root; ++ struct path path; ++ int err; ++ ++ ovl_path_upper(root_dentry, &path); ++ ++ err = vfs_statfs(&path, buf); ++ if (!err) { ++ buf->f_namelen = max(buf->f_namelen, ofs->lower_namelen); ++ buf->f_type = OVERLAYFS_SUPER_MAGIC; ++ } ++ ++ return err; ++} ++ ++/** ++ * ovl_show_options ++ * ++ * Prints the mount options for a given superblock. ++ * Returns zero; does not fail. ++ */ ++static int ovl_show_options(struct seq_file *m, struct dentry *dentry) ++{ ++ struct super_block *sb = dentry->d_sb; ++ struct ovl_fs *ufs = sb->s_fs_info; ++ ++ seq_printf(m, ",lowerdir=%s", ufs->config.lowerdir); ++ seq_printf(m, ",upperdir=%s", ufs->config.upperdir); ++ return 0; ++} ++ ++static const struct super_operations ovl_super_operations = { ++ .put_super = ovl_put_super, ++ .remount_fs = ovl_remount_fs, ++ .statfs = ovl_statfs, ++ .show_options = ovl_show_options, ++}; ++ ++enum { ++ Opt_lowerdir, ++ Opt_upperdir, ++ Opt_err, ++}; ++ ++static const match_table_t ovl_tokens = { ++ {Opt_lowerdir, "lowerdir=%s"}, ++ {Opt_upperdir, "upperdir=%s"}, ++ {Opt_err, NULL} ++}; ++ ++static int ovl_parse_opt(char *opt, struct ovl_config *config) ++{ ++ char *p; ++ ++ config->upperdir = NULL; ++ config->lowerdir = NULL; ++ ++ while ((p = strsep(&opt, ",")) != NULL) { ++ int token; ++ substring_t args[MAX_OPT_ARGS]; ++ ++ if (!*p) ++ continue; ++ ++ token = match_token(p, ovl_tokens, args); ++ switch (token) { ++ case Opt_upperdir: ++ kfree(config->upperdir); ++ config->upperdir = match_strdup(&args[0]); ++ if (!config->upperdir) ++ return -ENOMEM; ++ break; ++ ++ case Opt_lowerdir: ++ kfree(config->lowerdir); ++ config->lowerdir = match_strdup(&args[0]); ++ if (!config->lowerdir) ++ return -ENOMEM; ++ break; ++ ++ default: ++ return -EINVAL; ++ } ++ } ++ return 0; ++} ++ ++static int ovl_fill_super(struct super_block *sb, void *data, int silent) ++{ ++ struct path lowerpath; ++ struct path upperpath; ++ struct inode *root_inode; ++ struct dentry *root_dentry; ++ struct ovl_entry *oe; ++ struct ovl_fs *ufs; ++ struct kstatfs statfs; ++ int err; ++ ++ err = -ENOMEM; ++ ufs = kmalloc(sizeof(struct ovl_fs), GFP_KERNEL); ++ if (!ufs) ++ goto out; ++ ++ err = ovl_parse_opt((char *) data, &ufs->config); ++ if (err) ++ goto out_free_ufs; ++ ++ err = -EINVAL; ++ if (!ufs->config.upperdir || !ufs->config.lowerdir) { ++ printk(KERN_ERR "overlayfs: missing upperdir or lowerdir\n"); ++ goto out_free_config; ++ } ++ ++ oe = ovl_alloc_entry(); ++ if (oe == NULL) ++ goto out_free_config; ++ ++ err = kern_path(ufs->config.upperdir, LOOKUP_FOLLOW, &upperpath); ++ if (err) ++ goto out_free_oe; ++ ++ err = kern_path(ufs->config.lowerdir, LOOKUP_FOLLOW, &lowerpath); ++ if (err) ++ goto out_put_upperpath; ++ ++ err = -ENOTDIR; ++ if (!S_ISDIR(upperpath.dentry->d_inode->i_mode) || ++ !S_ISDIR(lowerpath.dentry->d_inode->i_mode)) ++ goto out_put_lowerpath; ++ ++ err = vfs_statfs(&lowerpath, &statfs); ++ if (err) { ++ printk(KERN_ERR "overlayfs: statfs failed on lowerpath\n"); ++ goto out_put_lowerpath; ++ } ++ ufs->lower_namelen = statfs.f_namelen; ++ ++ sb->s_stack_depth = max(upperpath.mnt->mnt_sb->s_stack_depth, ++ lowerpath.mnt->mnt_sb->s_stack_depth) + 1; ++ ++ err = -EINVAL; ++ if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) { ++ printk(KERN_ERR "overlayfs: maximum fs stacking depth exceeded\n"); ++ goto out_put_lowerpath; ++ } ++ ++ ++ ufs->upper_mnt = clone_private_mount(&upperpath); ++ err = PTR_ERR(ufs->upper_mnt); ++ if (IS_ERR(ufs->upper_mnt)) { ++ printk(KERN_ERR "overlayfs: failed to clone upperpath\n"); ++ goto out_put_lowerpath; ++ } ++ ++ ufs->lower_mnt = clone_private_mount(&lowerpath); ++ err = PTR_ERR(ufs->lower_mnt); ++ if (IS_ERR(ufs->lower_mnt)) { ++ printk(KERN_ERR "overlayfs: failed to clone lowerpath\n"); ++ goto out_put_upper_mnt; ++ } ++ ++ /* ++ * Make lower_mnt R/O. That way fchmod/fchown on lower file ++ * will fail instead of modifying lower fs. ++ */ ++ ufs->lower_mnt->mnt_flags |= MNT_READONLY; ++ ++ /* If the upper fs is r/o, we mark overlayfs r/o too */ ++ if (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY) ++ sb->s_flags |= MS_RDONLY; ++ ++ if (!(sb->s_flags & MS_RDONLY)) { ++ err = mnt_want_write(ufs->upper_mnt); ++ if (err) ++ goto out_put_lower_mnt; ++ } ++ ++ err = -ENOMEM; ++ root_inode = ovl_new_inode(sb, S_IFDIR, oe); ++ if (!root_inode) ++ goto out_drop_write; ++ ++ root_dentry = d_make_root(root_inode); ++ if (!root_dentry) ++ goto out_drop_write; ++ ++ mntput(upperpath.mnt); ++ mntput(lowerpath.mnt); ++ ++ oe->__upperdentry = dget(upperpath.dentry); ++ oe->lowerdentry = lowerpath.dentry; ++ ++ root_dentry->d_fsdata = oe; ++ root_dentry->d_op = &ovl_dentry_operations; ++ ++ sb->s_magic = OVERLAYFS_SUPER_MAGIC; ++ sb->s_op = &ovl_super_operations; ++ sb->s_root = root_dentry; ++ sb->s_fs_info = ufs; ++ ++ return 0; ++ ++out_drop_write: ++ if (!(sb->s_flags & MS_RDONLY)) ++ mnt_drop_write(ufs->upper_mnt); ++out_put_lower_mnt: ++ mntput(ufs->lower_mnt); ++out_put_upper_mnt: ++ mntput(ufs->upper_mnt); ++out_put_lowerpath: ++ path_put(&lowerpath); ++out_put_upperpath: ++ path_put(&upperpath); ++out_free_oe: ++ kfree(oe); ++out_free_config: ++ kfree(ufs->config.lowerdir); ++ kfree(ufs->config.upperdir); ++out_free_ufs: ++ kfree(ufs); ++out: ++ return err; ++} ++ ++static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags, ++ const char *dev_name, void *raw_data) ++{ ++ return mount_nodev(fs_type, flags, raw_data, ovl_fill_super); ++} ++ ++static struct file_system_type ovl_fs_type = { ++ .owner = THIS_MODULE, ++ .name = "overlayfs", ++ .mount = ovl_mount, ++ .kill_sb = kill_anon_super, ++}; ++ ++static int __init ovl_init(void) ++{ ++ return register_filesystem(&ovl_fs_type); ++} ++ ++static void __exit ovl_exit(void) ++{ ++ unregister_filesystem(&ovl_fs_type); ++} ++ ++module_init(ovl_init); ++module_exit(ovl_exit); +diff --git a/fs/splice.c b/fs/splice.c +index 718bd00..0e8f44a 100644 +--- a/fs/splice.c ++++ b/fs/splice.c +@@ -1308,6 +1308,7 @@ long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, + + return ret; + } ++EXPORT_SYMBOL(do_splice_direct); + + static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, + struct pipe_inode_info *opipe, +diff --git a/include/linux/fs.h b/include/linux/fs.h +index 2c28271..3353de6 100644 +--- a/include/linux/fs.h ++++ b/include/linux/fs.h +@@ -244,6 +244,12 @@ struct iattr { + */ + #include <linux/quota.h> + ++/* ++ * Maximum number of layers of fs stack. Needs to be limited to ++ * prevent kernel stack overflow ++ */ ++#define FILESYSTEM_MAX_STACK_DEPTH 2 ++ + /** + * enum positive_aop_returns - aop return codes with specific semantics + * +@@ -1320,6 +1326,11 @@ struct super_block { + + /* Being remounted read-only */ + int s_readonly_remount; ++ ++ /* ++ * Indicates how deep in a filesystem stack this SB is ++ */ ++ int s_stack_depth; + }; + + /* superblock cache pruning functions */ +@@ -1573,6 +1584,7 @@ struct inode_operations { + int (*atomic_open)(struct inode *, struct dentry *, + struct file *, unsigned open_flag, + umode_t create_mode, int *opened); ++ int (*dentry_open)(struct dentry *, struct file *, const struct cred *); + } ____cacheline_aligned; + + ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector, +@@ -2006,6 +2018,7 @@ extern struct file *file_open_name(struct filename *, int, umode_t); + extern struct file *filp_open(const char *, int, umode_t); + extern struct file *file_open_root(struct dentry *, struct vfsmount *, + const char *, int); ++extern int vfs_open(const struct path *, struct file *, const struct cred *); + extern struct file * dentry_open(const struct path *, int, const struct cred *); + extern int filp_close(struct file *, fl_owner_t id); + +@@ -2211,6 +2224,7 @@ extern sector_t bmap(struct inode *, sector_t); + #endif + extern int notify_change(struct dentry *, struct iattr *); + extern int inode_permission(struct inode *, int); ++extern int __inode_permission(struct inode *, int); + extern int generic_permission(struct inode *, int); + + static inline bool execute_ok(struct inode *inode) +diff --git a/include/linux/mount.h b/include/linux/mount.h +index d7029f4..344a262 100644 +--- a/include/linux/mount.h ++++ b/include/linux/mount.h +@@ -66,6 +66,9 @@ extern void mnt_pin(struct vfsmount *mnt); + extern void mnt_unpin(struct vfsmount *mnt); + extern int __mnt_is_readonly(struct vfsmount *mnt); + ++struct path; ++extern struct vfsmount *clone_private_mount(struct path *path); ++ + struct file_system_type; + extern struct vfsmount *vfs_kern_mount(struct file_system_type *type, + int flags, const char *name, |