kernel_optimize_test/fs
Darrick J. Wong d6f215f359 xfs: split up the xfs_reflink_end_cow work into smaller transactions
In xfs_reflink_end_cow, we allocate a single transaction for the entire
end_cow operation and then loop the CoW fork mappings to move them to
the data fork.  This design fails on a heavily fragmented filesystem
where an inode's data fork has exactly one more extent than would fit in
an extents-format fork, because the unmap can collapse the data fork
into extents format (freeing the bmbt block) but the remap can expand
the data fork back into a (newly allocated) bmbt block.  If the number
of extents we end up remapping is large, we can overflow the block
reservation because we reserved blocks assuming that we were adding
mappings into an already-cleared area of the data fork.

Let's say we have 8 extents in the data fork, 8 extents in the CoW fork,
and the data fork can hold at most 7 extents before needing to convert
to btree format; and that blocks A-P are discontiguous single-block
extents:

   0......7
D: ABCDEFGH
C: IJKLMNOP

When a write to file blocks 0-7 completes, we must remap I-P into the
data fork.  We start by removing H from the btree-format data fork.  Now
we have 7 extents, so we convert the fork to extents format, freeing the
bmbt block.   We then move P into the data fork and it now has 8 extents
again.  We must convert the data fork back to btree format, requiring a
block allocation.  If we repeat this sequence for blocks 6-5-4-3-2-1-0,
we'll need a total of 8 block allocations to remap all 8 blocks.  We
reserved only enough blocks to handle one btree split (5 blocks on a 4k
block filesystem), which means we overflow the block reservation.

To fix this issue, create a separate helper function to remap a single
extent, and change _reflink_end_cow to call it in a tight loop over the
entire range we're completing.  As a side effect this also removes the
size restrictions on how many extents we can end_cow at a time, though
nobody ever hit that.  It is not reasonable to reserve N blocks to remap
N blocks.

Note that this can be reproduced after ~320 million fsx ops while
running generic/938 (long soak directio fsx exerciser):

XFS: Assertion failed: tp->t_blk_res >= tp->t_blk_res_used, file: fs/xfs/xfs_trans.c, line: 116
<machine registers snipped>
Call Trace:
 xfs_trans_dup+0x211/0x250 [xfs]
 xfs_trans_roll+0x6d/0x180 [xfs]
 xfs_defer_trans_roll+0x10c/0x3b0 [xfs]
 xfs_defer_finish_noroll+0xdf/0x740 [xfs]
 xfs_defer_finish+0x13/0x70 [xfs]
 xfs_reflink_end_cow+0x2c6/0x680 [xfs]
 xfs_dio_write_end_io+0x115/0x220 [xfs]
 iomap_dio_complete+0x3f/0x130
 iomap_dio_rw+0x3c3/0x420
 xfs_file_dio_aio_write+0x132/0x3c0 [xfs]
 xfs_file_write_iter+0x8b/0xc0 [xfs]
 __vfs_write+0x193/0x1f0
 vfs_write+0xba/0x1c0
 ksys_write+0x52/0xc0
 do_syscall_64+0x50/0x160
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
2018-12-12 08:46:19 -08:00
..
9p Merge branch 'work.afs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-11-01 19:58:52 -07:00
adfs adfs: use timespec64 for time conversion 2018-08-22 10:52:51 -07:00
affs affs: fix potential memory leak when parsing option 'prefix' 2018-05-28 12:36:41 +02:00
afs Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-11-30 10:47:50 -08:00
autofs Merge branch 'akpm' (patches from Andrew) 2018-08-22 12:34:08 -07:00
befs fix a series of Documentation/ broken file name references 2018-06-15 18:10:01 -03:00
bfs bfs: add sanity check at bfs_fill_super() 2018-11-03 10:09:38 -07:00
btrfs for-4.20-rc5-tag 2018-12-05 09:58:17 -08:00
cachefiles fscache, cachefiles: remove redundant variable 'cache' 2018-11-30 16:00:58 +00:00
ceph libceph: assume argonaut on the server side 2018-11-08 17:51:11 +01:00
cifs CIFS: Avoid returning EBUSY to upper layer VFS 2018-12-07 00:59:23 -06:00
coda vfs: change inode times to use struct timespec64 2018-06-05 16:57:31 -07:00
configfs configfs: fix registered group removal 2018-07-17 06:14:07 -07:00
cramfs Make the Cramfs code more robust against filesystem corruptions, 2018-10-30 12:46:25 -07:00
crypto crypto: speck - remove Speck 2018-09-04 11:35:03 +08:00
debugfs Revert "debugfs: inode: debugfs_create_dir uses mode permission from parent" 2018-06-12 20:52:16 -07:00
devpts devpts: Convert to new IDA API 2018-08-21 23:54:17 -04:00
dlm iov_iter: Separate type from direction and use accessor functions 2018-10-24 00:41:07 +01:00
ecryptfs ecryptfs_rename(): verify that lower dentries are still OK after lock_rename() 2018-10-09 23:33:17 -04:00
efivarfs efivars: Call guid_parse() against guid_t type of variable 2018-07-22 14:13:44 +02:00
efs
exofs fs/exofs: only use true/false for asignment of bool type variable 2018-10-18 02:04:59 -04:00
exportfs exportfs: do not read dentry after free 2018-11-23 09:08:17 -05:00
ext2 ext2: fix potential use after free 2018-11-27 10:21:15 +01:00
ext4 A large number of ext4 bug fixes, mostly buffer and memory leaks on 2018-11-11 16:53:02 -06:00
f2fs Merge branch 'xarray' of git://git.infradead.org/users/willy/linux-dax 2018-10-28 11:35:40 -07:00
fat fat: truncate inode timestamp updates in setattr 2018-10-31 08:54:14 -07:00
freevxfs freevxfs_lookup(): use d_splice_alias() 2018-05-22 14:27:51 -04:00
fscache fscache: fix race between enablement and dropping of object 2018-11-30 15:57:31 +00:00
fuse fuse: fix use-after-free in fuse_direct_IO() 2018-11-09 15:52:17 +01:00
gfs2 Merge tag 'gfs2-4.20.fixes3' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2 2018-11-16 11:38:14 -06:00
hfs hfs: do not free node before using 2018-11-30 14:56:14 -08:00
hfsplus hfsplus: do not free node before using 2018-11-30 14:56:14 -08:00
hostfs vfs: discard ATTR_ATTR_FLAG 2018-08-17 16:20:28 -07:00
hpfs hpfs: remove unnecessary checks on the value of r when assigning error code 2018-08-25 12:42:33 -07:00
hugetlbfs mm: zero out the vma in vma_init() 2018-08-22 10:52:44 -07:00
isofs Update email address 2018-09-29 22:47:48 -04:00
jbd2 jbd2: fix use after free in jbd2_log_do_checkpoint() 2018-10-05 18:44:40 -04:00
jffs2 Merge branch 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2018-10-24 11:22:39 +01:00
jfs jfs: remove redundant dquot_initialize() in jfs_evict_inode() 2018-09-20 09:28:49 -05:00
kernfs mm: zero-seek shrinkers 2018-10-26 16:26:33 -07:00
lockd lockd: fix access beyond unterminated strings in prints 2018-10-29 16:58:04 -04:00
minix minix_lookup: use d_splice_alias() 2018-05-22 14:27:52 -04:00
nfs nfs: don't dirty kernel pages read by direct-io 2018-12-02 09:43:56 -05:00
nfs_common net: Drop pernet_operations::async 2018-03-27 13:18:09 -04:00
nfsd nfsd: COPY and CLONE operations require the saved filehandle to be set 2018-11-08 12:11:45 -05:00
nilfs2 nilfs2: Use xa_erase_irq 2018-11-05 14:57:05 -05:00
nls
notify fanotify: fix handling of events on child sub-directory 2018-11-08 15:43:48 +01:00
ntfs ntfs: don't open-code ERR_CAST 2018-10-12 22:46:50 -04:00
ocfs2 ocfs2: fix potential use after free 2018-11-30 14:56:15 -08:00
omfs omfs_lookup(): report IO errors, use d_splice_alias() 2018-05-22 14:27:58 -04:00
openpromfs openpromfs: switch to d_splice_alias() 2018-05-22 14:27:57 -04:00
orangefs Merge branch 'work.afs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-11-01 19:58:52 -07:00
overlayfs vfs: rework data cloning infrastructure 2018-11-02 09:33:08 -07:00
proc New gcc plugin: stackleak 2018-11-01 11:46:27 -07:00
pstore pstore fix: 2018-11-30 09:03:15 -08:00
qnx4 qnx4_lookup: use d_splice_alias() 2018-05-22 14:27:52 -04:00
qnx6 qnx6_lookup: switch to d_splice_alias() 2018-05-22 14:27:54 -04:00
quota fs/quota: Fix spectre gadget in do_quotactl 2018-08-22 18:17:48 +02:00
ramfs
reiserfs reiserfs: remove workaround code for GCC 3.x 2018-10-31 08:54:14 -07:00
romfs romfs_lookup: switch to d_splice_alias() 2018-05-22 14:27:55 -04:00
squashfs Squashfs: Compute expected length from inode size rather than block length 2018-08-02 09:34:02 -07:00
sysfs Driver core patches for 4.19-rc1 2018-08-18 11:44:53 -07:00
sysv sysv: return 'err' instead of 0 in __sysv_write_inode 2018-11-10 08:02:40 -05:00
tracefs tracefs: Annotate tracefs_ops with __ro_after_init 2018-07-31 11:32:44 -04:00
ubifs ubifs: Remove unneeded semicolon 2018-10-23 13:49:02 +02:00
udf udf: Allow mounting volumes with incorrect identification strings 2018-11-19 10:27:59 +01:00
ufs fs/ufs: use ktime_get_real_seconds for sb and cg timestamps 2018-08-17 16:20:27 -07:00
xfs xfs: split up the xfs_reflink_end_cow work into smaller transactions 2018-12-12 08:46:19 -08:00
aio.c aio: fix failure to put the file pointer 2018-11-17 10:05:07 -05:00
anon_inodes.c anon_inode_getfile(): switch to alloc_file_pseudo() 2018-07-12 10:04:27 -04:00
attr.c fs: Fix attr.c kernel-doc 2018-07-03 16:44:45 -04:00
bad_inode.c get rid of 'opened' argument of ->atomic_open() - part 3 2018-07-12 10:04:20 -04:00
binfmt_aout.c exec: introduce finalize_exec() before start_thread() 2018-04-11 10:28:37 -07:00
binfmt_elf_fdpic.c treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00
binfmt_elf.c signal: Distinguish between kernel_siginfo and siginfo 2018-10-03 16:47:43 +02:00
binfmt_em86.c
binfmt_flat.c exec: introduce finalize_exec() before start_thread() 2018-04-11 10:28:37 -07:00
binfmt_misc.c turn filp_clone_open() into inline wrapper for dentry_open() 2018-07-10 23:29:03 -04:00
binfmt_script.c
block_dev.c iov_iter: Use accessor function 2018-10-24 00:40:44 +01:00
buffer.c for-linus-20181102 2018-11-02 11:25:48 -07:00
char_dev.c block, char_dev: Use correct format specifier for unsigned ints 2018-03-15 17:59:24 +01:00
compat_binfmt_elf.c y2038: globally rename compat_time to old_time32 2018-08-27 14:48:48 +02:00
compat_ioctl.c media updates for v4.20-rc1 2018-10-29 14:29:58 -07:00
compat.c ncpfs: remove compat functionality 2018-06-05 19:23:26 +02:00
coredump.c signal: Distinguish between kernel_siginfo and siginfo 2018-10-03 16:47:43 +02:00
d_path.c split d_path() and friends into a separate file 2018-03-29 15:07:46 -04:00
dax.c dax: Fix unlock mismatch with updated API 2018-12-04 21:32:00 -08:00
dcache.c mm: remove include/linux/bootmem.h 2018-10-31 08:54:16 -07:00
dcookies.c fs: add do_lookup_dcookie() helper; remove in-kernel call to syscall 2018-04-02 20:15:39 +02:00
direct-io.c fs: fix lost error code in dio_complete 2018-11-30 08:35:14 -07:00
drop_caches.c
eventfd.c Revert changes to convert to ->poll_mask() and aio IOCB_CMD_POLL 2018-06-28 10:40:47 -07:00
eventpoll.c fs/eventpoll.c: simplify ep_is_linked() callers 2018-08-22 10:52:49 -07:00
exec.c Revert "exec: make de_thread() freezable" 2018-12-04 16:04:20 +01:00
fcntl.c signal: Distinguish between kernel_siginfo and siginfo 2018-10-03 16:47:43 +02:00
fhandle.c
file_table.c overlayfs update for 4.19 2018-08-21 18:19:09 -07:00
file.c fs: add ksys_close() wrapper; remove in-kernel calls to sys_close() 2018-04-02 20:16:00 +02:00
filesystems.c proc: introduce proc_create_single{,_data} 2018-05-16 07:23:35 +02:00
fs_pin.c
fs_struct.c
fs-writeback.c fs: Convert writeback to XArray 2018-10-21 10:46:42 -04:00
inode.c mm: don't reclaim inodes with many attached pages 2018-11-18 10:15:09 -08:00
internal.h overlayfs update for 4.19 2018-08-21 18:19:09 -07:00
ioctl.c vfs: rework data cloning infrastructure 2018-11-02 09:33:08 -07:00
iomap.c iomap: partially revert 4721a60109 (simulated directio short read on EFAULT) 2018-12-04 09:40:02 -08:00
Kconfig autofs: remove left-over autofs4 stubs 2018-06-11 08:22:34 -07:00
Kconfig.binfmt kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
libfs.c fs, dax: prepare for dax-specific address_space_operations 2018-03-30 11:34:55 -07:00
locks.c overlayfs update for 4.19 2018-08-21 18:19:09 -07:00
Makefile autofs: remove left-over autofs4 stubs 2018-06-11 08:22:34 -07:00
mbcache.c treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00
mount.h
mpage.c mpage: mpage_readpages() should submit IO as read-ahead 2018-08-17 16:20:29 -07:00
namei.c namei: allow restricted O_CREAT of FIFOs and regular files 2018-08-23 18:48:43 -07:00
namespace.c mnt: fix __detach_mounts infinite loop 2018-11-12 01:02:34 -06:00
no-block.c
nsfs.c
open.c overlayfs update for 4.19 2018-08-21 18:19:09 -07:00
pipe.c Merge branch 'work.open3' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-08-13 19:58:36 -07:00
pnode.c
pnode.h
posix_acl.c
proc_namespace.c
read_write.c vfs: allow some remap flags to be passed to vfs_clone_file_range 2018-12-04 08:50:49 -08:00
readdir.c fs: add ksys_getdents64() helper; remove in-kernel calls to sys_getdents64() 2018-04-02 20:16:02 +02:00
select.c y2038: globally rename compat_time to old_time32 2018-08-27 14:48:48 +02:00
seq_file.c fs/seq_file.c: simplify seq_file iteration code and interface 2018-08-17 16:20:28 -07:00
signalfd.c signal: Distinguish between kernel_siginfo and siginfo 2018-10-03 16:47:43 +02:00
splice.c splice: don't read more than available pipe space 2018-12-04 08:50:49 -08:00
stack.c
stat.c y2038: Remove newstat family from default syscall set 2018-08-29 15:42:20 +02:00
statfs.c kernel: add kcompat_sys_{f,}statfs64() 2018-07-12 14:49:48 +01:00
super.c fsnotify: add super block object type 2018-09-03 15:14:01 +02:00
sync.c Changes for this release: 2018-04-04 12:44:02 -07:00
timerfd.c y2038: globally rename compat_time to old_time32 2018-08-27 14:48:48 +02:00
userfaultfd.c userfaultfd: shmem/hugetlbfs: only allow to register VM_MAYWRITE vmas 2018-11-30 14:56:14 -08:00
utimes.c y2038: utimes: Rework #ifdef guards for compat syscalls 2018-08-29 15:42:23 +02:00
xattr.c sysfs: Do not return POSIX ACL xattrs via listxattr 2018-09-18 07:30:48 -04:00