Filipe Manana b850ae1427 Btrfs: fix deadlock between direct IO write and defrag/readpages ... If readpages() (triggered by defrag or buffered reads) is called while a direct IO write is in progress, we have a small time window where we can deadlock, resulting in traces like the following being generated: [84723.212993] INFO: task fio:2849 blocked for more than 120 seconds. [84723.214310] Tainted: G W 4.3.0-rc5-btrfs-next-17+ #1 [84723.215640] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [84723.217313] fio D ffff88023ec75218 0 2849 2835 0x00000000 [84723.218778] ffff880122dfb6e8 0000000000000092 0000000000000000 ffff88023ec75200 [84723.220458] ffff88000e05d2c0 ffff880122dfc000 ffff88023ec75200 7fffffffffffffff [84723.230597] 0000000000000002 ffffffff8147891a ffff880122dfb700 ffffffff8147856a [84723.232085] Call Trace: [84723.232625] [<ffffffff8147891a>] ? bit_wait+0x3c/0x3c [84723.233529] [<ffffffff8147856a>] schedule+0x7d/0x95 [84723.234398] [<ffffffff8147baa3>] schedule_timeout+0x43/0x10b [84723.235384] [<ffffffff810f82eb>] ? time_hardirqs_on+0x15/0x28 [84723.236426] [<ffffffff8108a23d>] ? trace_hardirqs_on+0xd/0xf [84723.237502] [<ffffffff810af8a3>] ? read_seqcount_begin.constprop.20+0x57/0x6d [84723.238807] [<ffffffff8108a09b>] ? trace_hardirqs_on_caller+0x16/0x1ab [84723.242012] [<ffffffff8108a23d>] ? trace_hardirqs_on+0xd/0xf [84723.243064] [<ffffffff810af2ad>] ? timekeeping_get_ns+0xe/0x33 [84723.244116] [<ffffffff810afa2e>] ? ktime_get+0x41/0x52 [84723.245029] [<ffffffff81477cff>] io_schedule_timeout+0xb7/0x12b [84723.245942] [<ffffffff81477cff>] ? io_schedule_timeout+0xb7/0x12b [84723.246596] [<ffffffff81478953>] bit_wait_io+0x39/0x45 [84723.247503] [<ffffffff81478b93>] __wait_on_bit_lock+0x49/0x8d [84723.248540] [<ffffffff8111684f>] __lock_page+0x66/0x68 [84723.249558] [<ffffffff81081c9b>] ? autoremove_wake_function+0x3a/0x3a [84723.250844] [<ffffffff81124a04>] lock_page+0x2c/0x2f [84723.251871] [<ffffffff81124afc>] invalidate_inode_pages2_range+0xf5/0x2aa [84723.253274] [<ffffffff81117c34>] ? filemap_fdatawait_range+0x12d/0x146 [84723.254757] [<ffffffff81118191>] ? filemap_fdatawrite_range+0x13/0x15 [84723.256378] [<ffffffffa05139a2>] btrfs_get_blocks_direct+0x1b0/0x664 [btrfs] [84723.258556] [<ffffffff8119e3f9>] ? submit_page_section+0x7b/0x111 [84723.260064] [<ffffffff8119eb90>] do_blockdev_direct_IO+0x658/0xbdb [84723.261479] [<ffffffffa05137f2>] ? btrfs_page_exists_in_range+0x1a9/0x1a9 [btrfs] [84723.262961] [<ffffffffa050a8a6>] ? btrfs_writepage_start_hook+0xce/0xce [btrfs] [84723.264449] [<ffffffff8119f144>] __blockdev_direct_IO+0x31/0x33 [84723.265614] [<ffffffff8119f144>] ? __blockdev_direct_IO+0x31/0x33 [84723.266769] [<ffffffffa050a8a6>] ? btrfs_writepage_start_hook+0xce/0xce [btrfs] [84723.268264] [<ffffffffa050935d>] btrfs_direct_IO+0x1b9/0x259 [btrfs] [84723.270954] [<ffffffffa050a8a6>] ? btrfs_writepage_start_hook+0xce/0xce [btrfs] [84723.272465] [<ffffffff8111878c>] generic_file_direct_write+0xb3/0x128 [84723.273734] [<ffffffffa051955c>] btrfs_file_write_iter+0x228/0x404 [btrfs] [84723.275101] [<ffffffff8116ca6f>] __vfs_write+0x7c/0xa5 [84723.276200] [<ffffffff8116cfab>] vfs_write+0xa0/0xe4 [84723.277298] [<ffffffff8116d79d>] SyS_write+0x50/0x7e [84723.278327] [<ffffffff8147cd97>] entry_SYSCALL_64_fastpath+0x12/0x6f [84723.279595] INFO: lockdep is turned off. [84723.379035] INFO: task btrfs:2923 blocked for more than 120 seconds. [84723.380323] Tainted: G W 4.3.0-rc5-btrfs-next-17+ #1 [84723.381608] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [84723.383003] btrfs D ffff88023ed75218 0 2923 2859 0x00000000 [84723.384277] ffff88001311f860 0000000000000082 ffff88001311f840 ffff88023ed75200 [84723.385748] ffff88012c6751c0 ffff880013120000 ffff88012042fe68 ffff88012042fe30 [84723.387152] ffff880221571c88 0000000000000001 ffff88001311f878 ffffffff8147856a [84723.388620] Call Trace: [84723.389105] [<ffffffff8147856a>] schedule+0x7d/0x95 [84723.391882] [<ffffffffa051da32>] btrfs_start_ordered_extent+0x161/0x1fa [btrfs] [84723.393718] [<ffffffff81081c61>] ? signal_pending_state+0x31/0x31 [84723.395659] [<ffffffffa0522c5b>] __do_contiguous_readpages.constprop.21+0x81/0xdc [btrfs] [84723.397383] [<ffffffffa050ac96>] ? btrfs_submit_direct+0x3f0/0x3f0 [btrfs] [84723.398852] [<ffffffffa0522da3>] __extent_readpages.constprop.20+0xed/0x100 [btrfs] [84723.400561] [<ffffffff81123f6c>] ? __lru_cache_add+0x5d/0x72 [84723.401787] [<ffffffffa0523896>] extent_readpages+0x111/0x1a7 [btrfs] [84723.403121] [<ffffffffa050ac96>] ? btrfs_submit_direct+0x3f0/0x3f0 [btrfs] [84723.404583] [<ffffffffa05088fa>] btrfs_readpages+0x1f/0x21 [btrfs] [84723.406007] [<ffffffff811226df>] __do_page_cache_readahead+0x168/0x1f4 [84723.407502] [<ffffffff81122988>] ondemand_readahead+0x21d/0x22e [84723.408937] [<ffffffff81122988>] ? ondemand_readahead+0x21d/0x22e [84723.410487] [<ffffffff81122af1>] page_cache_sync_readahead+0x3d/0x3f [84723.411710] [<ffffffffa0535388>] btrfs_defrag_file+0x419/0xaaf [btrfs] [84723.413007] [<ffffffffa0531db0>] ? kzalloc+0xf/0x11 [btrfs] [84723.414085] [<ffffffffa0535b43>] btrfs_ioctl_defrag+0x125/0x14e [btrfs] [84723.415307] [<ffffffffa0536753>] btrfs_ioctl+0x746/0x24c6 [btrfs] [84723.416532] [<ffffffff81087481>] ? arch_local_irq_save+0x9/0xc [84723.417731] [<ffffffff8113ad61>] ? __might_fault+0x4c/0xa7 [84723.418699] [<ffffffff8113ad61>] ? __might_fault+0x4c/0xa7 [84723.421532] [<ffffffff8113adba>] ? __might_fault+0xa5/0xa7 [84723.422629] [<ffffffff81171139>] ? cp_new_stat+0x15d/0x174 [84723.423712] [<ffffffff8117c610>] do_vfs_ioctl+0x427/0x4e6 [84723.424801] [<ffffffff81171175>] ? SYSC_newfstat+0x25/0x2e [84723.425968] [<ffffffff8118574d>] ? __fget_light+0x4d/0x71 [84723.427063] [<ffffffff8117c726>] SyS_ioctl+0x57/0x79 [84723.428138] [<ffffffff8147cd97>] entry_SYSCALL_64_fastpath+0x12/0x6f Consider the following logical and physical file layout: logical: ... [ prealloc extent A ] [ prealloc extent B ] [ extent C ] ... 4K 8K 16K physical: ... 12853248 12857344 1103101952 ... (= 12853248 + 4K) Extents A and B are physically adjacent. The following diagram shows a sequence of events that lead to the deadlock when we attempt to do a direct IO write against the file range [4K, 16K[ and a defrag is triggered simultaneously. CPU 1 CPU 2 btrfs_direct_IO() btrfs_get_blocks_direct() creates ordered extent A, covering the 4k prealloc extent A (range [4K, 8K[) btrfs_defrag_file() page_cache_sync_readahead([0K, 1M[) btrfs_readpages() extent_readpages() locks all pages in the file range [0K, 128K[ through calls to add_to_page_cache_lru() __do_contiguous_readpages() finds ordered extent A waits for it to complete btrfs_get_blocks_direct() called again lock_extent_direct(range [8K, 16K[) finds a page in range [8K, 16K[ through btrfs_page_exists_in_range() invalidate_inode_pages2_range([8K, 16K[) --> tries to lock pages that are already locked by the task at CPU 2 --> our task, running __blockdev_direct_IO(), hangs waiting to lock the pages and the submit bio callback, btrfs_submit_direct(), ends up never being called, resulting in the ordered extent A never completing (because a corresponding bio is never submitted) and CPU 2 will wait for it forever while holding the pages locked ---> deadlock! Fix this by removing the page invalidation approach when attempting to lock the range for IO from the callback btrfs_get_blocks_direct() and falling back buffered IO. This was a rare case anyway and well behaved applications do not mix concurrent direct IO writes with buffered reads anyway, being a concurrent defrag the only normal case that could lead to the deadlock. Signed-off-by: Filipe Manana <fdmanana@suse.com>		2015-12-17 10:59:50 +00:00
..
tests	Btrfs: tests: checking for NULL instead of IS_ERR()	2015-11-25 05:19:50 -08:00
acl.c	btrfs: remove useless ACL check	2014-06-09 17:20:42 -07:00
async-thread.c	btrfs: async_thread: Fix workqueue 'max_active' value when initializing	2015-08-31 11:46:40 -07:00
async-thread.h	btrfs: async_thread: Fix workqueue 'max_active' value when initializing	2015-08-31 11:46:40 -07:00
backref.c	Btrfs: use btrfs_get_fs_root in resolve_indirect_ref	2015-11-25 05:22:08 -08:00
backref.h	btrfs: cleanup, remove inode_item_info helper	2015-01-14 19:23:47 +01:00
btrfs_inode.h	Btrfs: Direct I/O: Fix space accounting	2015-09-21 13:47:55 -07:00
check-integrity.c	Merge branch 'cleanups/for-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus-4.4	2015-10-21 18:21:40 -07:00
check-integrity.h	block: submit_bio_wait() conversions	2013-11-24 16:33:41 -07:00
compression.c	Merge branch 'cleanups/for-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus-4.4	2015-10-21 18:21:40 -07:00
compression.h	btrfs: constify structs with op functions or static definitions	2015-02-16 18:48:44 +01:00
ctree.c	Merge branch 'cleanups/for-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus-4.4	2015-10-21 18:21:40 -07:00
ctree.h	Btrfs: fix scrub preventing unused block groups from being deleted	2015-11-25 05:22:08 -08:00
delayed-inode.c	btrfs: comment the rest of implicit barriers before waitqueue_active	2015-10-10 18:42:00 +02:00
delayed-inode.h	Btrfs: introduce the delayed inode ref deletion for the single link inode	2014-01-28 13:20:09 -08:00
delayed-ref.c	btrfs: qgroup: Fix a race in delayed_ref which leads to abort trans	2015-10-26 19:44:39 -07:00
delayed-ref.h	btrfs: qgroup: Fix a race in delayed_ref which leads to abort trans	2015-10-26 19:44:39 -07:00
dev-replace.c	Merge branch 'fix/waitqueue-barriers' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus-4.4	2015-10-12 16:24:40 -07:00
dev-replace.h
dir-item.c	Btrfs: make xattr replace operations atomic	2014-11-20 17:20:07 -08:00
disk-io.c	btrfs: qgroup: exit the rescan worker during umount	2015-11-05 10:32:20 +00:00
disk-io.h	Btrfs: add btrfs_read_dev_one_super() to read one specific SB	2015-10-01 17:29:38 +02:00
export.c	BTRFS: support NFSv2 export	2015-10-06 06:55:23 -07:00
export.h
extent_io.c	btrfs: extent_io: Introduce new function clear_record_extent_bits()	2015-10-21 18:37:44 -07:00
extent_io.h	btrfs: qgroup: Introduce btrfs_qgroup_reserve_data function	2015-10-21 18:37:45 -07:00
extent_map.c	Btrfs: do not move em to modified list when unpinning	2014-11-21 11:59:54 -08:00
extent_map.h	Btrfs: fix NULL pointer crash when running balance and scrub concurrently	2014-06-19 14:20:55 -07:00
extent-tree.c	Btrfs: fix unprotected list move from unused_bgs to deleted_bgs list	2015-12-10 11:22:38 +00:00
extent-tree.h	btrfs: qgroup: Add new qgroup calculation function	2015-06-10 09:25:49 -07:00
file-item.c	Merge branch 'cleanups-post-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus-4.1	2015-03-25 10:52:48 -07:00
file.c	Btrfs: check prepare_uptodate_page() error code earlier	2015-12-15 09:09:38 -08:00
free-space-cache.c	Merge branch 'for-chris-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/fdmanana/linux into for-linus-4.4	2015-12-15 09:09:59 -08:00
free-space-cache.h	Btrfs: keep track of largest extent in bitmaps	2015-10-21 18:55:40 -07:00
hash.c	btrfs: LLVMLinux: Remove VLAIS	2014-10-14 10:51:22 +02:00
hash.h	Btrfs: fix btrfs boot when compiled as built-in	2014-01-28 13:20:31 -08:00
inode-item.c	Btrfs: consolidate btrfs_error() to btrfs_std_error()	2015-09-29 16:30:00 +02:00
inode-map.c	btrfs: qgroup: Cleanup old inaccurate facilities	2015-10-21 18:41:06 -07:00
inode-map.h
inode.c	Btrfs: fix deadlock between direct IO write and defrag/readpages	2015-12-17 10:59:50 +00:00
ioctl.c	btrfs: check unsupported filters in balance arguments	2015-10-26 19:38:26 -07:00
Kconfig	rcu: Make SRCU optional by using CONFIG_SRCU	2015-01-06 11:04:29 -08:00
locking.c	btrfs: comment the rest of implicit barriers before waitqueue_active	2015-10-10 18:42:00 +02:00
locking.h	btrfs: fix lockups from btrfs_clear_path_blocking	2014-11-19 10:34:35 -08:00
lzo.c	btrfs: constify structs with op functions or static definitions	2015-02-16 18:48:44 +01:00
Makefile	Btrfs: add sanity tests for new qgroup accounting code	2014-06-09 17:20:49 -07:00
math.h	btrfs: cleanup 64bit/32bit divs, compile time constants	2015-03-03 17:23:57 +01:00
ordered-data.c	Btrfs: change how we wait for pending ordered extents	2015-10-21 18:51:40 -07:00
ordered-data.h	Btrfs: change how we wait for pending ordered extents	2015-10-21 18:51:40 -07:00
orphan.c	btrfs: kill the key type accessor helpers	2014-09-17 13:37:12 -07:00
print-tree.c	btrfs: remove parameter blocksize from read_tree_block	2014-10-02 17:14:50 +02:00
print-tree.h
props.c	btrfs: cleanup iterating over prop_handlers array	2015-10-21 18:28:48 +02:00
props.h	Btrfs: add support for inode properties	2014-01-28 13:20:24 -08:00
qgroup.c	btrfs: qgroup: account shared subtree during snapshot delete	2015-11-25 05:27:33 -08:00
qgroup.h	btrfs: qgroup: Check if qgroup reserved space leaked	2015-10-21 18:41:10 -07:00
raid56.c	btrfs: comment waitqueue_active implied by locks	2015-10-10 18:35:10 +02:00
raid56.h	Btrfs: add RAID 5/6 BTRFS_RBIO_REBUILD_MISSING operation	2015-08-09 07:34:26 -07:00
rcu-string.h
reada.c	btrfs: reada: Fix returned errno code	2015-10-21 18:29:50 +02:00
relocation.c	Btrfs: fix regression running delayed references when using qgroups	2015-10-25 19:53:26 +00:00
root-tree.c	Merge branch 'cleanups/for-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus-4.4	2015-10-21 18:21:40 -07:00
scrub.c	Btrfs: fix scrub preventing unused block groups from being deleted	2015-11-25 05:22:08 -08:00
send.c	btrfs: fix resending received snapshot with parent	2015-10-13 20:04:10 +01:00
send.h
struct-funcs.c
super.c	Btrfs: add fragment=* debug mount option	2015-10-21 18:51:43 -07:00
sysfs.c	Btrfs: rename super_kobj to fsid_kobj	2015-09-29 16:29:59 +02:00
sysfs.h	Btrfs: rename btrfs_kobj_rm_device to btrfs_sysfs_rm_device_link	2015-09-29 16:29:59 +02:00
transaction.c	Btrfs: fix memory leaks after transaction is aborted	2015-12-17 10:59:48 +00:00
transaction.h	Btrfs: fix unprotected list move from unused_bgs to deleted_bgs list	2015-12-10 11:22:38 +00:00
tree-defrag.c	Btrfs: cleanup: remove unnecessary check before btrfs_free_path is called	2015-08-31 11:46:41 -07:00
tree-log.c	Btrfs: fix regression running delayed references when using qgroups	2015-10-25 19:53:26 +00:00
tree-log.h	Btrfs: fix metadata inconsistencies after directory fsync	2015-03-26 17:56:23 -07:00
ulist.c	btrfs: ulist: Add ulist_del() function.	2015-06-10 09:26:17 -07:00
ulist.h	btrfs: ulist: Add ulist_del() function.	2015-06-10 09:26:17 -07:00
uuid-tree.c	Btrfs: make btrfs_search_forward return with nodes unlocked	2014-09-17 13:38:02 -07:00
volumes.c	Btrfs: fix race when finishing dev replace leading to transaction abort	2015-12-17 10:59:46 +00:00
volumes.h	btrfs: fix clashing number of the enhanced balance usage filter	2015-11-25 05:19:50 -08:00
xattr.c	Btrfs: fix race when listing an inode's xattrs	2015-11-09 18:34:40 +00:00
xattr.h	btrfs: use generic posix ACL infrastructure	2014-01-25 23:58:18 -05:00
zlib.c	btrfs: constify structs with op functions or static definitions	2015-02-16 18:48:44 +01:00