linux.git/fs/f2fs/segment.c, branch v5.1 Linux kernel source tree f2fs: fix to add refcount once page is tagged PG_private 2019-03-13T01:59:19+00:00 Chao Yu yuchao0@huawei.com 2019-03-06T09:30:59+00:00 240a59156d9bcfabceddb66be449e7b32fb5dc4a As Gao Xiang reported in bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=202749 f2fs may skip pageout() due to incorrect page reference count. The problem here is that MM defined the rule [1] very clearly that once page was set with PG_private flag, we should increment the refcount in that page, also main flows like pageout(), migrate_page() will assume there is one additional page reference count if page_has_private() returns true. But currently, f2fs won't add/del refcount when changing PG_private flag. Anyway, f2fs should follow MM's rule to make MM's related flows running as expected. [1] https://lore.kernel.org/lkml/2b19b3c4-2bc4-15fa-15cc-27a13e5c7af1@aol.com/ Reported-by: Gao Xiang <gaoxiang25@huawei.com> Signed-off-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> 
As Gao Xiang reported in bugzilla:

https://bugzilla.kernel.org/show_bug.cgi?id=202749

f2fs may skip pageout() due to incorrect page reference count.

The problem here is that MM defined the rule [1] very clearly that
once page was set with PG_private flag, we should increment the
refcount in that page, also main flows like pageout(), migrate_page()
will assume there is one additional page reference count if
page_has_private() returns true.

But currently, f2fs won't add/del refcount when changing PG_private
flag. Anyway, f2fs should follow MM's rule to make MM's related flows
running as expected.

[1] https://lore.kernel.org/lkml/2b19b3c4-2bc4-15fa-15cc-27a13e5c7af1@aol.com/

Reported-by: Gao Xiang <gaoxiang25@huawei.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: fix to avoid deadlock of atomic file operations 2019-03-13T01:59:19+00:00 Chao Yu yuchao0@huawei.com 2019-02-25T09:11:03+00:00 48432984d718c95cf13e26d487c2d1b697c3c01f Thread A Thread B - __fput - f2fs_release_file - drop_inmem_pages - mutex_lock(&fi->inmem_lock) - __revoke_inmem_pages - lock_page(page) - open - f2fs_setattr - truncate_setsize - truncate_inode_pages_range - lock_page(page) - truncate_cleanup_page - f2fs_invalidate_page - drop_inmem_page - mutex_lock(&fi->inmem_lock); We may encounter above ABBA deadlock as reported by Kyungtae Kim: I'm reporting a bug in linux-4.17.19: "INFO: task hung in drop_inmem_page" (no reproducer) I think this might be somehow related to the following: https://groups.google.com/forum/#!searchin/syzkaller-bugs/INFO$3A$20task$20hung$20in$20%7Csort:date/syzkaller-bugs/c6soBTrdaIo/AjAzPeIzCgAJ ========================================= INFO: task syz-executor7:10822 blocked for more than 120 seconds. Not tainted 4.17.19 #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor7 D27024 10822 6346 0x00000004 Call Trace: context_switch kernel/sched/core.c:2867 [inline] __schedule+0x721/0x1e60 kernel/sched/core.c:3515 schedule+0x88/0x1c0 kernel/sched/core.c:3559 schedule_preempt_disabled+0x18/0x30 kernel/sched/core.c:3617 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0x5bd/0x1410 kernel/locking/mutex.c:893 mutex_lock_nested+0x1b/0x20 kernel/locking/mutex.c:908 drop_inmem_page+0xcb/0x810 fs/f2fs/segment.c:327 f2fs_invalidate_page+0x337/0x5e0 fs/f2fs/data.c:2401 do_invalidatepage mm/truncate.c:165 [inline] truncate_cleanup_page+0x261/0x330 mm/truncate.c:187 truncate_inode_pages_range+0x552/0x1610 mm/truncate.c:367 truncate_inode_pages mm/truncate.c:478 [inline] truncate_pagecache+0x6d/0x90 mm/truncate.c:801 truncate_setsize+0x81/0xa0 mm/truncate.c:826 f2fs_setattr+0x44f/0x1270 fs/f2fs/file.c:781 notify_change+0xa62/0xe80 fs/attr.c:313 do_truncate+0x12e/0x1e0 fs/open.c:63 do_last fs/namei.c:2955 [inline] path_openat+0x2042/0x29f0 fs/namei.c:3505 do_filp_open+0x1bd/0x2c0 fs/namei.c:3540 do_sys_open+0x35e/0x4e0 fs/open.c:1101 __do_sys_open fs/open.c:1119 [inline] __se_sys_open fs/open.c:1114 [inline] __x64_sys_open+0x89/0xc0 fs/open.c:1114 do_syscall_64+0xc4/0x4e0 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4497b9 RSP: 002b:00007f734e459c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 00007f734e45a6cc RCX: 00000000004497b9 RDX: 0000000000000104 RSI: 00000000000a8280 RDI: 0000000020000080 RBP: 000000000071bea0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000007230 R14: 00000000006f02d0 R15: 00007f734e45a700 INFO: task syz-executor7:10858 blocked for more than 120 seconds. Not tainted 4.17.19 #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor7 D28880 10858 6346 0x00000004 Call Trace: context_switch kernel/sched/core.c:2867 [inline] __schedule+0x721/0x1e60 kernel/sched/core.c:3515 schedule+0x88/0x1c0 kernel/sched/core.c:3559 __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:565 [inline] rwsem_down_write_failed+0x5e6/0xc90 kernel/locking/rwsem-xadd.c:594 call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:117 __down_write arch/x86/include/asm/rwsem.h:142 [inline] down_write+0x58/0xa0 kernel/locking/rwsem.c:72 inode_lock include/linux/fs.h:713 [inline] do_truncate+0x120/0x1e0 fs/open.c:61 do_last fs/namei.c:2955 [inline] path_openat+0x2042/0x29f0 fs/namei.c:3505 do_filp_open+0x1bd/0x2c0 fs/namei.c:3540 do_sys_open+0x35e/0x4e0 fs/open.c:1101 __do_sys_open fs/open.c:1119 [inline] __se_sys_open fs/open.c:1114 [inline] __x64_sys_open+0x89/0xc0 fs/open.c:1114 do_syscall_64+0xc4/0x4e0 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4497b9 RSP: 002b:00007f734e3b4c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 00007f734e3b56cc RCX: 00000000004497b9 RDX: 0000000000000104 RSI: 00000000000a8280 RDI: 0000000020000080 RBP: 000000000071c238 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000007230 R14: 00000000006f02d0 R15: 00007f734e3b5700 INFO: task syz-executor5:10829 blocked for more than 120 seconds. Not tainted 4.17.19 #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor5 D28760 10829 6308 0x80000002 Call Trace: context_switch kernel/sched/core.c:2867 [inline] __schedule+0x721/0x1e60 kernel/sched/core.c:3515 schedule+0x88/0x1c0 kernel/sched/core.c:3559 io_schedule+0x21/0x80 kernel/sched/core.c:5179 wait_on_page_bit_common mm/filemap.c:1100 [inline] __lock_page+0x2b5/0x390 mm/filemap.c:1273 lock_page include/linux/pagemap.h:483 [inline] __revoke_inmem_pages+0xb35/0x11c0 fs/f2fs/segment.c:231 drop_inmem_pages+0xa3/0x3e0 fs/f2fs/segment.c:306 f2fs_release_file+0x2c7/0x330 fs/f2fs/file.c:1556 __fput+0x2c7/0x780 fs/file_table.c:209 ____fput+0x1a/0x20 fs/file_table.c:243 task_work_run+0x151/0x1d0 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x8ba/0x30a0 kernel/exit.c:865 do_group_exit+0x13b/0x3a0 kernel/exit.c:968 get_signal+0x6bb/0x1650 kernel/signal.c:2482 do_signal+0x84/0x1b70 arch/x86/kernel/signal.c:810 exit_to_usermode_loop+0x155/0x190 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] syscall_return_slowpath arch/x86/entry/common.c:265 [inline] do_syscall_64+0x445/0x4e0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4497b9 RSP: 002b:00007f1c68e74ce8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 000000000071bf80 RCX: 00000000004497b9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000071bf80 RBP: 000000000071bf80 R08: 0000000000000000 R09: 000000000071bf58 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f1c68e759c0 R15: 00007f1c68e75700 This patch tries to use trylock_page to mitigate such deadlock condition for fix. Signed-off-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> 
Thread A				Thread B
- __fput
 - f2fs_release_file
  - drop_inmem_pages
   - mutex_lock(&fi->inmem_lock)
   - __revoke_inmem_pages
    - lock_page(page)
					- open
					- f2fs_setattr
					- truncate_setsize
					 - truncate_inode_pages_range
					  - lock_page(page)
					  - truncate_cleanup_page
					   - f2fs_invalidate_page
					    - drop_inmem_page
					    - mutex_lock(&fi->inmem_lock);

We may encounter above ABBA deadlock as reported by Kyungtae Kim:

I'm reporting a bug in linux-4.17.19: "INFO: task hung in
drop_inmem_page" (no reproducer)

I think this might be somehow related to the following:
https://groups.google.com/forum/#!searchin/syzkaller-bugs/INFO$3A$20task$20hung$20in$20%7Csort:date/syzkaller-bugs/c6soBTrdaIo/AjAzPeIzCgAJ

=========================================
INFO: task syz-executor7:10822 blocked for more than 120 seconds.
      Not tainted 4.17.19 #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor7   D27024 10822   6346 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2867 [inline]
 __schedule+0x721/0x1e60 kernel/sched/core.c:3515
 schedule+0x88/0x1c0 kernel/sched/core.c:3559
 schedule_preempt_disabled+0x18/0x30 kernel/sched/core.c:3617
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock+0x5bd/0x1410 kernel/locking/mutex.c:893
 mutex_lock_nested+0x1b/0x20 kernel/locking/mutex.c:908
 drop_inmem_page+0xcb/0x810 fs/f2fs/segment.c:327
 f2fs_invalidate_page+0x337/0x5e0 fs/f2fs/data.c:2401
 do_invalidatepage mm/truncate.c:165 [inline]
 truncate_cleanup_page+0x261/0x330 mm/truncate.c:187
 truncate_inode_pages_range+0x552/0x1610 mm/truncate.c:367
 truncate_inode_pages mm/truncate.c:478 [inline]
 truncate_pagecache+0x6d/0x90 mm/truncate.c:801
 truncate_setsize+0x81/0xa0 mm/truncate.c:826
 f2fs_setattr+0x44f/0x1270 fs/f2fs/file.c:781
 notify_change+0xa62/0xe80 fs/attr.c:313
 do_truncate+0x12e/0x1e0 fs/open.c:63
 do_last fs/namei.c:2955 [inline]
 path_openat+0x2042/0x29f0 fs/namei.c:3505
 do_filp_open+0x1bd/0x2c0 fs/namei.c:3540
 do_sys_open+0x35e/0x4e0 fs/open.c:1101
 __do_sys_open fs/open.c:1119 [inline]
 __se_sys_open fs/open.c:1114 [inline]
 __x64_sys_open+0x89/0xc0 fs/open.c:1114
 do_syscall_64+0xc4/0x4e0 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4497b9
RSP: 002b:00007f734e459c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f734e45a6cc RCX: 00000000004497b9
RDX: 0000000000000104 RSI: 00000000000a8280 RDI: 0000000020000080
RBP: 000000000071bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000007230 R14: 00000000006f02d0 R15: 00007f734e45a700
INFO: task syz-executor7:10858 blocked for more than 120 seconds.
      Not tainted 4.17.19 #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor7   D28880 10858   6346 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2867 [inline]
 __schedule+0x721/0x1e60 kernel/sched/core.c:3515
 schedule+0x88/0x1c0 kernel/sched/core.c:3559
 __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:565 [inline]
 rwsem_down_write_failed+0x5e6/0xc90 kernel/locking/rwsem-xadd.c:594
 call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:117
 __down_write arch/x86/include/asm/rwsem.h:142 [inline]
 down_write+0x58/0xa0 kernel/locking/rwsem.c:72
 inode_lock include/linux/fs.h:713 [inline]
 do_truncate+0x120/0x1e0 fs/open.c:61
 do_last fs/namei.c:2955 [inline]
 path_openat+0x2042/0x29f0 fs/namei.c:3505
 do_filp_open+0x1bd/0x2c0 fs/namei.c:3540
 do_sys_open+0x35e/0x4e0 fs/open.c:1101
 __do_sys_open fs/open.c:1119 [inline]
 __se_sys_open fs/open.c:1114 [inline]
 __x64_sys_open+0x89/0xc0 fs/open.c:1114
 do_syscall_64+0xc4/0x4e0 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4497b9
RSP: 002b:00007f734e3b4c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f734e3b56cc RCX: 00000000004497b9
RDX: 0000000000000104 RSI: 00000000000a8280 RDI: 0000000020000080
RBP: 000000000071c238 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000007230 R14: 00000000006f02d0 R15: 00007f734e3b5700
INFO: task syz-executor5:10829 blocked for more than 120 seconds.
      Not tainted 4.17.19 #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor5   D28760 10829   6308 0x80000002
Call Trace:
 context_switch kernel/sched/core.c:2867 [inline]
 __schedule+0x721/0x1e60 kernel/sched/core.c:3515
 schedule+0x88/0x1c0 kernel/sched/core.c:3559
 io_schedule+0x21/0x80 kernel/sched/core.c:5179
 wait_on_page_bit_common mm/filemap.c:1100 [inline]
 __lock_page+0x2b5/0x390 mm/filemap.c:1273
 lock_page include/linux/pagemap.h:483 [inline]
 __revoke_inmem_pages+0xb35/0x11c0 fs/f2fs/segment.c:231
 drop_inmem_pages+0xa3/0x3e0 fs/f2fs/segment.c:306
 f2fs_release_file+0x2c7/0x330 fs/f2fs/file.c:1556
 __fput+0x2c7/0x780 fs/file_table.c:209
 ____fput+0x1a/0x20 fs/file_table.c:243
 task_work_run+0x151/0x1d0 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x8ba/0x30a0 kernel/exit.c:865
 do_group_exit+0x13b/0x3a0 kernel/exit.c:968
 get_signal+0x6bb/0x1650 kernel/signal.c:2482
 do_signal+0x84/0x1b70 arch/x86/kernel/signal.c:810
 exit_to_usermode_loop+0x155/0x190 arch/x86/entry/common.c:162
 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
 do_syscall_64+0x445/0x4e0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4497b9
RSP: 002b:00007f1c68e74ce8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000071bf80 RCX: 00000000004497b9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000071bf80
RBP: 000000000071bf80 R08: 0000000000000000 R09: 000000000071bf58
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f1c68e759c0 R15: 00007f1c68e75700

This patch tries to use trylock_page to mitigate such deadlock condition
for fix.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: fix to update iostat correctly in IPU path 2019-03-13T01:59:18+00:00 Chao Yu yuchao0@huawei.com 2019-02-21T12:40:13+00:00 e46f6bd82c831d20f9b6c149076cf5d2c443d638 In error path of IPU, we didn't account iostat correctly, fix it. Signed-off-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> 
In error path of IPU, we didn't account iostat correctly, fix it.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: make fault injection covering __submit_flush_wait() 2019-03-13T01:59:18+00:00 Chao Yu yuchao0@huawei.com 2019-02-19T09:08:18+00:00 dc37910d4c63296513c5795187d020ad9793822b This patch changes to allow failure of f2fs_bio_alloc() in __submit_flush_wait(), which can simulate flush error in checkpoint() for covering more error paths. Signed-off-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> 
This patch changes to allow failure of f2fs_bio_alloc() in
__submit_flush_wait(), which can simulate flush error in checkpoint()
for covering more error paths.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: try to keep CP_TRIMMED_FLAG after successful umount 2019-02-16T04:59:45+00:00 Jaegeuk Kim jaegeuk@kernel.org 2019-01-25T17:12:13+00:00 b86232536c3ec068b0960ffc62c61a872412b2b7 If every discard were issued successfully, we can avoid further discard. Reviewed-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> 
If every discard were issued successfully, we can avoid further discard.

Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: add quick mode of checkpoint=disable for QA 2019-02-16T04:59:37+00:00 Jaegeuk Kim jaegeuk@kernel.org 2019-01-25T01:48:38+00:00 db610a640eeeb268c36a4558414f28e1c269433e This mode returns mount() quickly with EAGAIN. We can trigger this by shutdown(F2FS_GOING_DOWN_NEED_FSCK). Reviewed-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> 
This mode returns mount() quickly with EAGAIN. We can trigger this by
shutdown(F2FS_GOING_DOWN_NEED_FSCK).

Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: run discard jobs when put_super 2019-02-04T16:55:34+00:00 Jaegeuk Kim jaegeuk@kernel.org 2019-01-14T18:42:11+00:00 03f2c02d8be76d2080c174cd65d2dfcbbf783708 When we umount f2fs, we need to avoid long delay due to discard commands, which is actually taking tens of seconds, if storage is very slow on UNMAP. So, this patch introduces timeout-based work on it. By default, let me give 5 seconds for discard. Reviewed-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> 
When we umount f2fs, we need to avoid long delay due to discard commands, which
is actually taking tens of seconds, if storage is very slow on UNMAP. So, this
patch introduces timeout-based work on it.

By default, let me give 5 seconds for discard.

Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: check PageWriteback flag for ordered case 2018-12-26T23:16:56+00:00 Chao Yu yuchao0@huawei.com 2018-12-25T09:43:42+00:00 bae0ee7a767ceeea6d8e170da3f228fbc7480331 For all ordered cases in f2fs_wait_on_page_writeback(), we need to check PageWriteback status, so let's clean up to relocate the check into f2fs_wait_on_page_writeback(). Signed-off-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> 
For all ordered cases in f2fs_wait_on_page_writeback(), we need to
check PageWriteback status, so let's clean up to relocate the check
into f2fs_wait_on_page_writeback().

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: fix block address for __check_sit_bitmap 2018-12-26T23:16:55+00:00 Qiuyang Sun sunqiuyang@huawei.com 2018-12-18T09:32:23+00:00 9249dded7b5cb539a8c8698b25d08a3c15261470 Should use lstart (logical start address) instead of start (in dev) here. This fixes a bug in multi-device scenarios. Signed-off-by: Qiuyang Sun <sunqiuyang@huawei.com> Reviewed-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> 
Should use lstart (logical start address) instead of start (in dev) here.
This fixes a bug in multi-device scenarios.

Signed-off-by: Qiuyang Sun <sunqiuyang@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs: flush stale issued discard candidates 2018-12-26T23:16:54+00:00 Jaegeuk Kim jaegeuk@kernel.org 2018-12-14T04:50:51+00:00 76c7bfb3a89371aa87bda99c8ee2611ff5150434 Sometimes, I could observe # of issuing_discard to be 1 which blocks background jobs due to is_idle()=false. The only way to get out of it was to trigger gc_urgent. This patch avoids that by checking any candidates as done in the list. Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> 
Sometimes, I could observe # of issuing_discard to be 1 which blocks background
jobs due to is_idle()=false.
The only way to get out of it was to trigger gc_urgent. This patch avoids that
by checking any candidates as done in the list.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>