BMC/Intel-BMC/linux.git/fs/overlayfs/super.c, branch dev

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2015-07-05T02:36:06+00:00

Pull more vfs updates from Al Viro: "Assorted VFS fixes and related cleanups (IMO the most interesting in that part are f_path-related things and Eric's descriptor-related stuff). UFS regression fixes (it got broken last cycle). 9P fixes. fs-cache series, DAX patches, Jan's file_remove_suid() work" [ I'd say this is much more than "fixes and related cleanups". The file_table locking rule change by Eric Dumazet is a rather big and fundamental update even if the patch isn't huge. - Linus ] * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (49 commits) 9p: cope with bogus responses from server in p9_client_{read,write} p9_client_write(): avoid double p9_free_req() 9p: forgetting to cancel request on interrupted zero-copy RPC dax: bdev_direct_access() may sleep block: Add support for DAX reads/writes to block devices dax: Use copy_from_iter_nocache dax: Add block size note to documentation fs/file.c: __fget() and dup2() atomicity rules fs/file.c: don't acquire files->file_lock in fd_install() fs:super:get_anon_bdev: fix race condition could cause dev exceed its upper limitation vfs: avoid creation of inode number 0 in get_next_ino namei: make set_root_rcu() return void make simple_positive() public ufs: use dir_pages instead of ufs_dir_pages() pagemap.h: move dir_pages() over there remove the pointless include of lglock.h fs: cleanup slight list_entry abuse xfs: Correctly lock inode when removing suid and file capabilities fs: Call security_ops->inode_killpriv on truncate fs: Provide function telling whether file_remove_privs() will do anything ...

ovl: allow distributed fs as lower layer

2015-06-22T11:53:48+00:00

Allow filesystems with .d_revalidate as lower layer(s), but not as upper layer. For local filesystems the rule was that modifications on the layers directly while being part of the overlay results in undefined behavior. This can easily be extended to distributed filesystems: we assume the tree used as lower layer is static, which means ->d_revalidate() should always return "1". If that is not the case, return -ESTALE, don't try to work around the modification. Signed-off-by: Miklos Szeredi

ovl: don't traverse automount points

2015-06-22T11:53:48+00:00

NFS and other distributed filesystems may place automount points in the tree. Previoulsy overlayfs refused to mount such filesystems types (based on the existence of the .d_automount callback), even if the actual export didn't have any automount points. It cannot be determined in advance whether the filesystem has automount points or not. The solution is to allow fs with .d_automount but refuse to traverse any automount points encountered. Signed-off-by: Miklos Szeredi

overlayfs: Make f_path always point to the overlay and f_inode to the underlay

2015-06-19T07:19:32+00:00

Make file->f_path always point to the overlay dentry so that the path in /proc/pid/fd is correct and to ensure that label-based LSMs have access to the overlay as well as the underlay (path-based LSMs probably don't need it). Using my union testsuite to set things up, before the patch I see: [root@andromeda union-testsuite]# bash 5 /a/foo107 [root@andromeda union-testsuite]# stat /mnt/a/foo107 ... Device: 23h/35d Inode: 13381 Links: 1 ... [root@andromeda union-testsuite]# stat -L /proc/$$/fd/5 ... Device: 23h/35d Inode: 13381 Links: 1 ... After the patch: [root@andromeda union-testsuite]# bash 5 /mnt/a/foo107 [root@andromeda union-testsuite]# stat /mnt/a/foo107 ... Device: 23h/35d Inode: 40346 Links: 1 ... [root@andromeda union-testsuite]# stat -L /proc/$$/fd/5 ... Device: 23h/35d Inode: 40346 Links: 1 ... Note the change in where /proc/$$/fd/5 points to in the ls command. It was pointing to /a/foo107 (which doesn't exist) and now points to /mnt/a/foo107 (which is correct). The inode accessed, however, is the lower layer. The union layer is on device 25h/37d and the upper layer on 24h/36d. Signed-off-by: David Howells Signed-off-by: Al Viro

ovl: mount read-only if workdir can't be created

2015-05-19T12:30:12+00:00

OpenWRT folks reported that overlayfs fails to mount if upper fs is full, because workdir can't be created. Wordir creation can fail for various other reasons too. There's no reason that the mount itself should fail, overlayfs can work fine without a workdir, as long as the overlay isn't modified. So mount it read-only and don't allow remounting read-write. Add a couple of WARN_ON()s for the impossible case of workdir being used despite being read-only. Reported-by: Bastian Bittorf Signed-off-by: Miklos Szeredi Cc: # v3.18+

ovl: upper fs should not be R/O

2015-03-18T09:29:48+00:00

After importing multi-lower layer support, users could mount a r/o partition as the left most lowerdir instead of using it as upperdir. And a r/o upperdir may cause an error like overlayfs: failed to create directory ./workdir/work during mount. This patch check the *s_flags* of upper fs and return an error if it is a r/o partition. The checking of *upper_mnt->mnt_sb->s_flags* can be removed now. This patch also remove /* FIXME: workdir is not needed for a R/O mount */ from ovl_fill_super() because: 1) for upper fs r/o case Setting a r/o partition as upper is prevented, no need to care about workdir in this case. 2) for "mount overlay -o ro" with a r/w upper fs case Users could remount overlayfs to r/w in this case, so workdir should not be omitted. Signed-off-by: hujianyang Signed-off-by: Miklos Szeredi

ovl: check lowerdir amount for non-upper mount

2015-03-18T09:29:47+00:00

Recently multi-lower layer mount support allow upperdir and workdir to be omitted, then cause overlayfs can be mount with only one lowerdir directory. This action make no sense and have potential risk. This patch check the total number of lower directories to prevent mounting overlayfs with only one directory. Also, an error message is added to indicate lower directories exceed OVL_MAX_STACK limit. Signed-off-by: hujianyang Signed-off-by: Miklos Szeredi

ovl: print error message for invalid mount options

2015-03-18T09:29:47+00:00

Overlayfs should print an error message if an incorrect mount option is caught like other filesystems. After this patch, improper option input could be clearly known. Reported-by: Fabian Sturm Signed-off-by: hujianyang Signed-off-by: Miklos Szeredi

ovl: Prevent rw remount when it should be ro mount

2015-01-08T13:47:21+00:00

Overlayfs should be mounted read-only when upper-fs is read-only or nonexistent. But now it can be remounted read-write and this can cause kernel panic. So we should prevent read-write remount when the above situation happens. Signed-off-by: Seunghun Lee Signed-off-by: Miklos Szeredi

ovl: Fix opaque regression in ovl_lookup

2015-01-08T13:47:20+00:00

Current multi-layer support overlayfs has a regression in .lookup(). If there is a directory in upperdir and a regular file has same name in lowerdir in a merged directory, lower file is hidden and upper directory is set to opaque in former case. But it is changed in present code. In lowerdir lookup path, if a found inode is not directory, the type checking of previous inode is missing. This inode will be copied to the lowerstack of ovl_entry directly. That will lead to several wrong conditions, for example, the reading of the directory in upperdir may return an error like: ls: reading directory .: Not a directory This patch makes the lowerdir lookup path check the opaque for non-directory file too. Signed-off-by: hujianyang Signed-off-by: Miklos Szeredi