linux/fs, branch v3.4.58

vfs: d_obtain_alias() needs to use "/" as default name.

2013-08-15T05:57:08Z

commit b911a6bdeef5848c468597d040e3407e0aee04ce upstream. NFS appears to use d_obtain_alias() to create the root dentry rather than d_make_root. This can cause 'prepend_path()' to complain that the root has a weird name if an NFS filesystem is lazily unmounted. e.g. if "/mnt" is an NFS mount then { cd /mnt; umount -l /mnt ; ls -l /proc/self/cwd; } will cause a WARN message like WARNING: at /home/git/linux/fs/dcache.c:2624 prepend_path+0x1d7/0x1e0() ... Root dentry has weird name <> to appear in kernel logs. So change d_obtain_alias() to use "/" rather than "" as the anonymous name. Signed-off-by: NeilBrown Cc: Trond Myklebust Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Al Viro [bwh: Backported to 3.2: use named initialisers instead of QSTR_INIT()] Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman

debugfs: debugfs_remove_recursive() must not rely on list_empty(d_subdirs)

2013-08-15T05:57:07Z

commit 776164c1faac4966ab14418bb0922e1820da1d19 upstream. debugfs_remove_recursive() is wrong, 1. it wrongly assumes that !list_empty(d_subdirs) means that this dir should be removed. This is not that bad by itself, but: 2. if d_subdirs does not becomes empty after __debugfs_remove() it gives up and silently fails, it doesn't even try to remove other entries. However ->d_subdirs can be non-empty because it still has the already deleted !debugfs_positive() entries. 3. simple_release_fs() is called even if __debugfs_remove() fails. Suppose we have dir1/ dir2/ file2 file1 and someone opens dir1/dir2/file2. Now, debugfs_remove_recursive(dir1/dir2) succeeds, and dir1/dir2 goes away. But debugfs_remove_recursive(dir1) silently fails and doesn't remove this directory. Because it tries to delete (the already deleted) dir1/dir2/file2 again and then fails due to "Avoid infinite loop" logic. Test-case: #!/bin/sh cd /sys/kernel/debug/tracing echo 'p:probe/sigprocmask sigprocmask' >> kprobe_events sleep 1000 < events/probe/sigprocmask/id & echo -n >| kprobe_events [ -d events/probe ] && echo "ERR!! failed to rm probe" And after that it is not possible to create another probe entry. With this patch debugfs_remove_recursive() skips !debugfs_positive() files although this is not strictly needed. The most important change is that it does not try to make ->d_subdirs empty, it simply scans the whole list(s) recursively and removes as much as possible. Link: http://lkml.kernel.org/r/20130726151256.GC19472@redhat.com Acked-by: Greg Kroah-Hartman Signed-off-by: Oleg Nesterov Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman

cifs: extend the buffer length enought for sprintf() using

2013-08-15T05:57:07Z

commit 057d6332b24a4497c55a761c83c823eed9e3f23b upstream. For cifs_set_cifscreds() in "fs/cifs/connect.c", 'desc' buffer length is 'CIFSCREDS_DESC_SIZE' (56 is less than 256), and 'ses->domainName' length may be "255 + '\0'". The related sprintf() may cause memory overflow, so need extend related buffer enough to hold all things. It is also necessary to be sure of 'ses->domainName' must be less than 256, and define the related macro instead of hard code number '256'. Signed-off-by: Chen Gang Reviewed-by: Jeff Layton Reviewed-by: Shirish Pargaonkar Reviewed-by: Scott Lovenberg Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman

ext4: fix mount/remount error messages for incompatible mount options

2013-08-15T05:57:07Z

commit 6ae6514b33f941d3386da0dfbe2942766eab1577 upstream. Commit 5688978 ("ext4: improve handling of conflicting mount options") introduced incorrect messages shown while choosing wrong mount options. First of all, both cases of incorrect mount options, "data=journal,delalloc" and "data=journal,dioread_nolock" result in the same error message. Secondly, the problem above isn't solved for remount option: the mismatched parameter is simply ignored. Moreover, ext4_msg states that remount with options "data=journal,delalloc" succeeded, which is not true. To fix it up, I added a simple check after parse_options() call to ensure that data=journal and delalloc/dioread_nolock parameters are not present at the same time. Signed-off-by: Piotr Sarna Acked-by: Bartlomiej Zolnierkiewicz Signed-off-by: Kyungmin Park Signed-off-by: "Theodore Ts'o" Signed-off-by: Greg Kroah-Hartman

ext4: make sure group number is bumped after a inode allocation race

2013-08-15T05:57:06Z

commit a34eb503742fd25155fd6cff6163daacead9fbc3 upstream. When we try to allocate an inode, and there is a race between two CPU's trying to grab the same inode, _and_ this inode is the last free inode in the block group, make sure the group number is bumped before we continue searching the rest of the block groups. Otherwise, we end up searching the current block group twice, and we end up skipping searching the last block group. So in the unlikely situation where almost all of the inodes are allocated, it's possible that we will return ENOSPC even though there might be free inodes in that last block group. Signed-off-by: "Theodore Ts'o" Signed-off-by: Greg Kroah-Hartman

fanotify: info leak in copy_event_to_user()

2013-08-11T22:38:43Z

commit de1e0c40aceb9d5bff09c3a3b97b2f1b178af53f upstream. The ->reserved field isn't cleared so we leak one byte of stack information to userspace. Signed-off-by: Dan Carpenter Cc: Eric Paris Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Cc: Luis Henriques Signed-off-by: Greg Kroah-Hartman

livelock avoidance in sget()

2013-08-04T08:25:59Z

commit acfec9a5a892f98461f52ed5770de99a3e571ae2 upstream. Eric Sandeen has found a nasty livelock in sget() - take a mount(2) about to fail. The superblock is on ->fs_supers, ->s_umount is held exclusive, ->s_active is 1. Along comes two more processes, trying to mount the same thing; sget() in each is picking that superblock, bumping ->s_count and trying to grab ->s_umount. ->s_active is 3 now. Original mount(2) finally gets to deactivate_locked_super() on failure; ->s_active is 2, superblock is still ->fs_supers because shutdown will *not* happen until ->s_active hits 0. ->s_umount is dropped and now we have two processes chasing each other: s_active = 2, A acquired ->s_umount, B blocked A sees that the damn thing is stillborn, does deactivate_locked_super() s_active = 1, A drops ->s_umount, B gets it A restarts the search and finds the same superblock. And bumps it ->s_active. s_active = 2, B holds ->s_umount, A blocked on trying to get it ... and we are in the earlier situation with A and B switched places. The root cause, of course, is that ->s_active should not grow until we'd got MS_BORN. Then failing ->mount() will have deactivate_locked_super() shut the damn thing down. Fortunately, it's easy to do - the key point is that grab_super() is called only for superblocks currently on ->fs_supers, so it can bump ->s_count and grab ->s_umount first, then check MS_BORN and bump ->s_active; we must never increment ->s_count for superblocks past ->kill_sb(), but grab_super() is never called for those. The bug is pretty old; we would've caught it by now, if not for accidental exclusion between sget() for block filesystems; the things like cgroup or e.g. mtd-based filesystems don't have anything of that sort, so they get bitten. The right way to deal with that is obviously to fix sget()... Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman

Btrfs: re-add root to dead root list if we stop dropping it

2013-08-04T08:25:54Z

commit d29a9f629e009c9b90e5859bce581070fd6247fc upstream. If we stop dropping a root for whatever reason we need to add it back to the dead root list so that we will re-start the dropping next transaction commit. The other case this happens is if we recover a drop because we will add a root without adding it to the fs radix tree, so we can leak it's root and commit root extent buffer, adding this to the dead root list makes this cleanup happen. Thanks, Reported-by: Alex Lyakas Signed-off-by: Josef Bacik Signed-off-by: Greg Kroah-Hartman

Btrfs: fix lock leak when resuming snapshot deletion

2013-08-04T08:25:54Z

commit fec386ac1428f9c0e672df952cbca5cebd4e4e2f upstream. We aren't setting path->locks[level] when we resume a snapshot deletion which means we won't unlock the buffer when we free the path. This causes deadlocks if we happen to re-allocate the block before we've evicted the extent buffer from cache. Thanks, Reported-by: Alex Lyakas Signed-off-by: Josef Bacik Signed-off-by: Greg Kroah-Hartman

lockd: protect nlm_blocked access in nlmsvc_retry_blocked

2013-07-28T23:26:17Z

commit 1c327d962fc420aea046c16215a552710bde8231 upstream. In nlmsvc_retry_blocked, the check that the list is non-empty and acquiring the pointer of the first entry is unprotected by any lock. This allows a rare race condition when there is only one entry on the list. A function such as nlmsvc_grant_callback() can be called, which will temporarily remove the entry from the list. Between the list_empty() and list_entry(),the list may become empty, causing an invalid pointer to be used as an nlm_block, leading to a possible crash. This patch adds the nlm_block_lock around these calls to prevent concurrent use of the nlm_blocked list. This was a regression introduced by f904be9cc77f361d37d71468b13ff3d1a1823dea "lockd: Mostly remove BKL from the server". Signed-off-by: David Jeffery Cc: Bryan Schumaker Signed-off-by: J. Bruce Fields Signed-off-by: Greg Kroah-Hartman