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9f54180109
linux-next/fs
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Dave Chinner 9f54180109 xfs: concurrent readdir hangs on data buffer locks 
There's a three-process deadlock involving shared/exclusive barriers
and inverted lock orders in the directory readdir implementation.
It's a pre-existing problem with lock ordering, exposed by the
VFS parallelisation code.

process 1               process 2               process 3
---------               ---------               ---------
readdir
iolock(shared)
  get_leaf_dents
    iterate entries
       ilock(shared)
       map, lock and read buffer
       iunlock(shared)
       process entries in buffer
       .....
                                                readdir
                                                iolock(shared)
                                                  get_leaf_dents
                                                    iterate entries
                                                      ilock(shared)
                                                      map, lock buffer
                                                      <blocks>
                        finish ->iterate_shared
                        file_accessed()
                          ->update_time
                            start transaction
                            ilock(excl)
                            <blocks>
        .....
        finishes processing buffer
        get next buffer
          ilock(shared)
          <blocks>

And that's the deadlock.

Fix this by dropping the current buffer lock in process 1 before
trying to map the next buffer. This means we keep the lock order of
ilock -> buffer lock intact and hence will allow process 3 to make
progress and drop it's ilock(shared) once it is done.

Reported-by: Xiong Zhou <xzhou@redhat.com>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-18 13:20:21 -04:00
..
9p 9p: switch to ->iterate_shared() 2016-05-09 11:41:16 -04:00
adfs fs/adfs/adfs.h: tidy up comments 2016-01-20 17:09:18 -08:00
affs simple local filesystems: switch to ->iterate_shared() 2016-05-02 19:49:32 -04:00
afs afs: switch to ->iterate_shared() 2016-05-10 14:27:44 -04:00
autofs4 dcache_{readdir,dir_lseek}() users: switch to ->iterate_shared 2016-05-02 19:49:32 -04:00
befs befs: switch to ->iterate_shared() 2016-05-10 14:24:57 -04:00
bfs more trivial ->iterate_shared conversions 2016-05-09 11:41:14 -04:00
btrfs Revert "btrfs: switch to ->iterate_shared()" 2016-05-18 13:19:17 -04:00
cachefiles mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
ceph Merge getxattr prototype change into work.lookups 2016-05-02 19:45:47 -04:00
cifs cifs: switch to ->iterate_shared() 2016-05-02 19:49:31 -04:00
coda introduce a parallel variant of ->iterate() 2016-05-02 19:49:29 -04:00
configfs configfs_readdir(): make safe under shared lock 2016-05-09 11:41:13 -04:00
cramfs more trivial ->iterate_shared conversions 2016-05-09 11:41:14 -04:00
crypto mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
debugfs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
devpts pty: make sure super_block is still valid in final /dev/tty close 2016-02-06 23:45:46 -08:00
dlm mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
ecryptfs switch ecryptfs to ->iterate_shared 2016-05-09 11:42:18 -04:00
efivarfs mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
efs more trivial ->iterate_shared conversions 2016-05-09 11:41:14 -04:00
exofs more trivial ->iterate_shared conversions 2016-05-09 11:41:14 -04:00
exportfs introduce a parallel variant of ->iterate() 2016-05-02 19:49:29 -04:00
ext2 simple local filesystems: switch to ->iterate_shared() 2016-05-02 19:49:32 -04:00
ext4 ext4: switch to ->iterate_shared() 2016-05-12 20:36:01 -04:00
f2fs f2fs: switch to ->iterate_shared() 2016-05-10 16:41:13 -04:00
fat fat: switch to ->iterate_shared() 2016-05-09 11:41:15 -04:00
freevxfs more trivial ->iterate_shared conversions 2016-05-09 11:41:14 -04:00
fscache mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
fuse fuse: switch to ->iterate_shared() 2016-05-02 19:49:31 -04:00
gfs2 gfs2: switch to ->iterate_shared() 2016-05-12 17:00:20 -04:00
hfs hfs: switch to ->iterate_shared() 2016-05-12 20:13:50 -04:00
hfsplus hfsplus: switch to ->iterate_shared() 2016-05-12 20:08:40 -04:00
hostfs hostfs: switch to ->iterate_shared() 2016-05-12 19:49:30 -04:00
hpfs hpfs: switch to ->iterate_shared() 2016-05-12 19:47:13 -04:00
hugetlbfs mm, fs: remove remaining PAGE_CACHE_* and page_cache_{get,release} usage 2016-04-04 10:41:08 -07:00
isofs isofs: switch to ->iterate_shared() 2016-05-09 12:53:03 -04:00
jbd2 mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
jffs2 more trivial ->iterate_shared conversions 2016-05-09 11:41:14 -04:00
jfs Merge getxattr prototype change into work.lookups 2016-05-02 19:45:47 -04:00
kernfs kernfs: no point locking directory around that generic_file_llseek() 2016-05-09 11:41:13 -04:00
lockd lockd: constify nlmsvc_binding structure 2016-01-07 10:10:50 -05:00
logfs logfs: no need to lock directory in lseek 2016-05-09 11:42:19 -04:00
minix simple local filesystems: switch to ->iterate_shared() 2016-05-02 19:49:32 -04:00
ncpfs mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
nfs nfs: per-name sillyunlink exclusion 2016-05-09 11:39:45 -04:00
nfs_common
nfsd don't bother with ->d_inode->i_sb - it's always equal to ->d_sb 2016-04-10 17:11:51 -04:00
nilfs2 more trivial ->iterate_shared conversions 2016-05-09 11:41:14 -04:00
nls
notify fsnotify: turn fsnotify reaper thread into a workqueue job 2016-02-18 16:23:24 -08:00
ntfs mm, fs: remove remaining PAGE_CACHE_* and page_cache_{get,release} usage 2016-04-04 10:41:08 -07:00
ocfs2 parallel lookups: actual switch to rwsem 2016-05-02 19:49:28 -04:00
omfs more trivial ->iterate_shared conversions 2016-05-09 11:41:14 -04:00
openpromfs more trivial ->iterate_shared conversions 2016-05-09 11:41:14 -04:00
orangefs orangefs: don't open-code inode_lock/inode_unlock 2016-05-02 19:47:23 -04:00
overlayfs parallel lookups: actual switch to rwsem 2016-05-02 19:49:28 -04:00
proc switch all procfs directories ->iterate_shared() 2016-05-02 19:49:30 -04:00
pstore mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
qnx4 more trivial ->iterate_shared conversions 2016-05-09 11:41:14 -04:00
qnx6 more trivial ->iterate_shared conversions 2016-05-09 11:41:14 -04:00
quota quota: Handle Q_GETNEXTQUOTA when quota is disabled 2016-03-29 17:20:10 +02:00
ramfs mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
reiserfs more trivial ->iterate_shared conversions 2016-05-09 11:41:14 -04:00
romfs romfs, squashfs: switch to ->iterate_shared() 2016-05-09 11:41:15 -04:00
squashfs romfs, squashfs: switch to ->iterate_shared() 2016-05-09 11:41:15 -04:00
sysfs platform/chrome: Branch for v4.4 2015-11-13 21:53:18 -08:00
sysv simple local filesystems: switch to ->iterate_shared() 2016-05-02 19:49:32 -04:00
tracefs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
ubifs more trivial ->iterate_shared conversions 2016-05-09 11:41:14 -04:00
udf more trivial ->iterate_shared conversions 2016-05-09 11:41:14 -04:00
ufs simple local filesystems: switch to ->iterate_shared() 2016-05-02 19:49:32 -04:00
xfs xfs: concurrent readdir hangs on data buffer locks 2016-05-18 13:20:21 -04:00
aio.c
anon_inodes.c
attr.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
bad_inode.c ->getxattr(): pass dentry and inode as separate arguments 2016-04-11 00:48:00 -04:00
binfmt_aout.c
binfmt_elf_fdpic.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
binfmt_elf.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
binfmt_em86.c
binfmt_flat.c
binfmt_misc.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
binfmt_script.c
block_dev.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
buffer.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
char_dev.c
compat_binfmt_elf.c
compat_ioctl.c Merge 4.5-rc4 into char-misc-next 2016-02-14 14:25:59 -08:00
compat.c give readdir(2)/getdents(2)/etc. uniform exclusion with lseek() 2016-05-02 19:49:28 -04:00
coredump.c fs/coredump: prevent fsuid=0 dumps into user-controlled directories 2016-03-22 15:36:02 -07:00
dax.c mm, fs: remove remaining PAGE_CACHE_* and page_cache_{get,release} usage 2016-04-04 10:41:08 -07:00
dcache.c parallel lookups: actual switch to rwsem 2016-05-02 19:49:28 -04:00
dcookies.c
direct-io.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
drop_caches.c
eventfd.c eventfd: document lockless access in eventfd_poll 2016-03-22 15:36:02 -07:00
eventpoll.c timer: convert timer_slack_ns from unsigned long to u64 2016-03-17 15:09:34 -07:00
exec.c Merge branch 'mm-pkeys-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-20 19:08:56 -07:00
fcntl.c fcntl: allow to set O_DIRECT flag on pipe 2016-01-09 02:55:37 -05:00
fhandle.c fs/coredump: prevent fsuid=0 dumps into user-controlled directories 2016-03-22 15:36:02 -07:00
file_table.c
file.c give readdir(2)/getdents(2)/etc. uniform exclusion with lseek() 2016-05-02 19:49:28 -04:00
filesystems.c find_filesystem(): simplify comparison 2016-01-19 12:02:23 -05:00
fs_pin.c
fs_struct.c
fs-writeback.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
inode.c parallel lookups: actual switch to rwsem 2016-05-02 19:49:28 -04:00
internal.h Merge branch 'for-linus' into work.misc 2016-01-08 21:20:11 -05:00
ioctl.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
Kconfig Merge tag 'ofs-pull-tag-1' of git://git.kernel.org/pub/scm/linux/kernel/git/hubcap/linux 2016-03-26 12:59:04 -07:00
Kconfig.binfmt
libfs.c more trivial ->iterate_shared conversions 2016-05-09 11:41:14 -04:00
locks.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
Makefile Merge tag 'ofs-pull-tag-1' of git://git.kernel.org/pub/scm/linux/kernel/git/hubcap/linux 2016-03-26 12:59:04 -07:00
mbcache.c mbcache: add reusable flag to cache entries 2016-02-22 22:44:04 -05:00
mount.h
mpage.c mm, fs: remove remaining PAGE_CACHE_* and page_cache_{get,release} usage 2016-04-04 10:41:08 -07:00
namei.c lookup_open(): lock the parent shared unless O_CREAT is given 2016-05-02 19:51:17 -04:00
namespace.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
no-block.c
nsfs.c
open.c give readdir(2)/getdents(2)/etc. uniform exclusion with lseek() 2016-05-02 19:49:28 -04:00
pipe.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
pnode.c fs/pnode.c: treat zero mnt_group_id-s as unequal 2016-02-20 00:15:52 -05:00
pnode.h
posix_acl.c xattr_handler: pass dentry and inode as separate arguments of ->get() 2016-04-10 20:48:24 -04:00
proc_namespace.c vfs: show_vfsstat: do not ignore errors from show_devname method 2016-03-16 13:09:08 -04:00
read_write.c give readdir(2)/getdents(2)/etc. uniform exclusion with lseek() 2016-05-02 19:49:28 -04:00
readdir.c introduce a parallel variant of ->iterate() 2016-05-02 19:49:29 -04:00
select.c timer: convert timer_slack_ns from unsigned long to u64 2016-03-17 15:09:34 -07:00
seq_file.c
signalfd.c
splice.c Merge branch 'for-linus' into work.lookups 2016-05-02 19:49:46 -04:00
stack.c
stat.c fs/stat.c: drop the last new_valid_dev check 2016-01-16 11:17:23 -08:00
statfs.c
super.c writeback: flush inode cgroup wb switches instead of pinning super_block 2016-03-03 14:42:50 -07:00
sync.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
timerfd.c timerfd: Handle relative timers with CONFIG_TIME_LOW_RES proper 2016-01-17 11:13:55 +01:00
userfaultfd.c userfaultfd: don't block on the last VM updates at exit time 2016-03-02 09:03:18 -08:00
utimes.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
xattr.c ->getxattr(): pass dentry and inode as separate arguments 2016-04-11 00:48:00 -04:00