kernel/linux.git/fs/overlayfs/readdir.c, branch linux-6.0.y

ovl: handle idmappings for layer lookup

2022-04-28T14:31:12+00:00

Make the two places where lookup helpers can be called either on lower or upper layers take the mount's idmapping into account. To this end we pass down the mount in struct ovl_lookup_data. It can later also be used to construct struct path for various other helpers. This is needed to support idmapped base layers with overlay. Cc: Tested-by: Giuseppe Scrivano Reviewed-by: Amir Goldstein Signed-off-by: Christian Brauner (Microsoft) Signed-off-by: Miklos Szeredi

ovl: use ovl_lookup_upper() wrapper

2022-04-28T14:31:11+00:00

Introduce ovl_lookup_upper() as a simple wrapper around lookup_one(). Make it clear in the helper's name that this only operates on the upper layer. The wrapper will take upper layer's idmapping into account when checking permission in lookup_one(). Cc: Tested-by: Giuseppe Scrivano Reviewed-by: Amir Goldstein Signed-off-by: Christian Brauner (Microsoft) Signed-off-by: Miklos Szeredi

ovl: pass ofs to creation operations

2022-04-28T14:31:10+00:00

Pass down struct ovl_fs to all creation helpers so we can ultimately retrieve the relevant upper mount and take the mount's idmapping into account when creating new filesystem objects. This is needed to support idmapped base layers with overlay. Cc: Tested-by: Giuseppe Scrivano Reviewed-by: Amir Goldstein Signed-off-by: Christian Brauner (Microsoft) Signed-off-by: Miklos Szeredi

ovl: use wrappers to all vfs_*xattr() calls

2022-04-28T14:31:10+00:00

Use helpers ovl_*xattr() to access user/trusted.overlay.* xattrs and use helpers ovl_do_*xattr() to access generic xattrs. This is a preparatory patch for using idmapped base layers with overlay. Note that a few of those places called vfs_*xattr() calls directly to reduce the amount of debug output. But as Miklos pointed out since overlayfs has been stable for quite some time the debug output isn't all that relevant anymore and the additional debug in all locations was actually quite helpful when developing this patch series. Cc: Tested-by: Giuseppe Scrivano Reviewed-by: Christian Brauner (Microsoft) Signed-off-by: Amir Goldstein Signed-off-by: Christian Brauner (Microsoft) Signed-off-by: Miklos Szeredi

ovl: skip stale entries in merge dir cache iteration

2021-08-10T08:21:30+00:00

On the first getdents call, ovl_iterate() populates the readdir cache with a list of entries, but for upper entries with origin lower inode, p->ino remains zero. Following getdents calls traverse the readdir cache list and call ovl_cache_update_ino() for entries with zero p->ino to lookup the entry in the overlay and return d_ino that is consistent with st_ino. If the upper file was unlinked between the first getdents call and the getdents call that lists the file entry, ovl_cache_update_ino() will not find the entry and fall back to setting d_ino to the upper real st_ino, which is inconsistent with how this object was presented to users. Instead of listing a stale entry with inconsistent d_ino, simply skip the stale entry, which is better for users. xfstest overlay/077 is failing without this patch. Signed-off-by: Amir Goldstein Link: https://lore.kernel.org/fstests/CAOQ4uxgR_cLnC_vdU5=seP3fwqVkuZM_-WfD6maFTMbMYq=a9w@mail.gmail.com/ Signed-off-by: Miklos Szeredi

Merge tag 'ovl-update-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs

2021-04-30T22:17:08+00:00

Pull overlayfs update from Miklos Szeredi: - Fix a regression introduced in 5.2 that resulted in valid overlayfs mounts being rejected with ELOOP (Too many levels of symbolic links) - Fix bugs found by various tools - Miscellaneous improvements and cleanups * tag 'ovl-update-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs: ovl: add debug print to ovl_do_getxattr() ovl: invalidate readdir cache on changes to dir with origin ovl: allow upperdir inside lowerdir ovl: show "userxattr" in the mount data ovl: trivial typo fixes in the file inode.c ovl: fix misspellings using codespell tool ovl: do not copy attr several times ovl: remove ovl_map_dev_ino() return value ovl: fix error for ovl_fill_super() ovl: fix missing revert_creds() on error path ovl: fix leaked dentry ovl: restrict lower null uuid for "xino=auto" ovl: check that upperdir path is not on a read-only mount ovl: plumb through flush method

ovl: remove unneeded ioctls

2021-04-12T13:04:30+00:00

The FS_IOC_[GS]ETFLAGS/FS_IOC_FS[GS]ETXATTR ioctls are now handled via the fileattr api. The only unconverted filesystem remaining is CIFS and it is not allowed to be overlayed due to case insensitive filenames. Signed-off-by: Miklos Szeredi

ovl: invalidate readdir cache on changes to dir with origin

2021-04-12T10:00:37+00:00

The test in ovl_dentry_version_inc() was out-dated and did not include the case where readdir cache is used on a non-merge dir that has origin xattr, indicating that it may contain leftover whiteouts. To make the code more robust, use the same helper ovl_dir_is_real() to determine if readdir cache should be used and if readdir cache should be invalidated. Fixes: b79e05aaa166 ("ovl: no direct iteration for dir with origin xattr") Link: https://lore.kernel.org/linux-unionfs/CAOQ4uxht70nODhNHNwGFMSqDyOKLXOKrY0H6g849os4BQ7cokA@mail.gmail.com/ Cc: Chris Murphy Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: implement volatile-specific fsync error behaviour

2021-01-28T09:22:48+00:00

Overlayfs's volatile option allows the user to bypass all forced sync calls to the upperdir filesystem. This comes at the cost of safety. We can never ensure that the user's data is intact, but we can make a best effort to expose whether or not the data is likely to be in a bad state. The best way to handle this in the time being is that if an overlayfs's upperdir experiences an error after a volatile mount occurs, that error will be returned on fsync, fdatasync, sync, and syncfs. This is contradictory to the traditional behaviour of VFS which fails the call once, and only raises an error if a subsequent fsync error has occurred, and been raised by the filesystem. One awkward aspect of the patch is that we have to manually set the superblock's errseq_t after the sync_fs callback as opposed to just returning an error from syncfs. This is because the call chain looks something like this: sys_syncfs -> sync_filesystem -> __sync_filesystem -> /* The return value is ignored here sb->s_op->sync_fs(sb) _sync_blockdev /* Where the VFS fetches the error to raise to userspace */ errseq_check_and_advance Because of this we call errseq_set every time the sync_fs callback occurs. Due to the nature of this seen / unseen dichotomy, if the upperdir is an inconsistent state at the initial mount time, overlayfs will refuse to mount, as overlayfs cannot get a snapshot of the upperdir's errseq that will increment on error until the user calls syncfs. Signed-off-by: Sargun Dhillon Suggested-by: Amir Goldstein Reviewed-by: Amir Goldstein Fixes: c86243b090bc ("ovl: provide a mount option "volatile"") Cc: stable@vger.kernel.org Reviewed-by: Vivek Goyal Reviewed-by: Jeff Layton Signed-off-by: Miklos Szeredi

ovl: avoid deadlock on directory ioctl

2021-01-28T09:22:48+00:00

The function ovl_dir_real_file() currently uses the inode lock to serialize writes to the od->upperfile field. However, this function will get called by ovl_ioctl_set_flags(), which utilizes the inode lock too. In this case ovl_dir_real_file() will try to claim a lock that is owned by a function in its call stack, which won't get released before ovl_dir_real_file() returns. Fix by replacing the open coded compare and exchange by an explicit atomic op. Fixes: 61536bed2149 ("ovl: support [S|G]ETFLAGS and FS[S|G]ETXATTR ioctls for directories") Cc: stable@vger.kernel.org # v5.10 Reported-by: Icenowy Zheng Tested-by: Icenowy Zheng Signed-off-by: Miklos Szeredi