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f2fs: finish previous checkpoints before returning from remount

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Flush remaining checkpoint requests at the end of remount, since a new
checkpoint would be triggered while remount and we need to take care of
it before returning from remount, in order to avoid the below race
condition.

  - Thread                          - checkpoint thread
  do_remount()
   down_write(&sb->s_umount);
   f2fs_remount()
    f2fs_disable_checkpoint(sbi) -> add checkpoints to the list
                                    block_operations()
                                     down_read_trylock(&sb->s_umount) = 0
   up_write(&sb->s_umount);
                                     f2fs_quota_sync()
                                      dquot_writeback_dquots()
                                       WARN_ON_ONCE(!rwsem_is_locked(&sb->s_umount));

Signed-off-by: Daeho Jeong <daehojeong@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Daeho Jeong 2023-10-20 09:36:45 -07:00 committed by Jaegeuk Kim
parent 9b4c8dd99f
commit 1e7bef5f90
1 changed files with 32 additions and 27 deletions

59
fs/f2fs/super.c

@ -2319,9 +2319,9 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
unsigned long old_sb_flags;
int err;
bool need_restart_gc = false, need_stop_gc = false;
bool need_restart_ckpt = false, need_stop_ckpt = false;
bool need_restart_flush = false, need_stop_flush = false;
bool need_restart_discard = false, need_stop_discard = false;
bool need_enable_checkpoint = false, need_disable_checkpoint = false;
bool no_read_extent_cache = !test_opt(sbi, READ_EXTENT_CACHE);
bool no_age_extent_cache = !test_opt(sbi, AGE_EXTENT_CACHE);
bool enable_checkpoint = !test_opt(sbi, DISABLE_CHECKPOINT);
@ -2485,24 +2485,6 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
clear_sbi_flag(sbi, SBI_IS_CLOSE);
}
if ((*flags & SB_RDONLY) || test_opt(sbi, DISABLE_CHECKPOINT) ||
!test_opt(sbi, MERGE_CHECKPOINT)) {
f2fs_stop_ckpt_thread(sbi);
need_restart_ckpt = true;
} else {
/* Flush if the prevous checkpoint, if exists. */
f2fs_flush_ckpt_thread(sbi);
err = f2fs_start_ckpt_thread(sbi);
if (err) {
f2fs_err(sbi,
"Failed to start F2FS issue_checkpoint_thread (%d)",
err);
goto restore_gc;
}
need_stop_ckpt = true;
}
/*
* We stop issue flush thread if FS is mounted as RO
* or if flush_merge is not passed in mount option.
@ -2514,7 +2496,7 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
} else {
err = f2fs_create_flush_cmd_control(sbi);
if (err)
goto restore_ckpt;
goto restore_gc;
need_stop_flush = true;
}
@ -2536,8 +2518,31 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
err = f2fs_disable_checkpoint(sbi);
if (err)
goto restore_discard;
need_enable_checkpoint = true;
} else {
f2fs_enable_checkpoint(sbi);
need_disable_checkpoint = true;
}
}
/*
* Place this routine at the end, since a new checkpoint would be
* triggered while remount and we need to take care of it before
* returning from remount.
*/
if ((*flags & SB_RDONLY) || test_opt(sbi, DISABLE_CHECKPOINT) ||
!test_opt(sbi, MERGE_CHECKPOINT)) {
f2fs_stop_ckpt_thread(sbi);
} else {
/* Flush if the prevous checkpoint, if exists. */
f2fs_flush_ckpt_thread(sbi);
err = f2fs_start_ckpt_thread(sbi);
if (err) {
f2fs_err(sbi,
"Failed to start F2FS issue_checkpoint_thread (%d)",
err);
goto restore_checkpoint;
}
}
@ -2555,6 +2560,13 @@ skip:
adjust_unusable_cap_perc(sbi);
*flags = (*flags & ~SB_LAZYTIME) | (sb->s_flags & SB_LAZYTIME);
return 0;
restore_checkpoint:
if (need_enable_checkpoint) {
f2fs_enable_checkpoint(sbi);
} else if (need_disable_checkpoint) {
if (f2fs_disable_checkpoint(sbi))
f2fs_warn(sbi, "checkpoint has not been disabled");
}
restore_discard:
if (need_restart_discard) {
if (f2fs_start_discard_thread(sbi))
@ -2570,13 +2582,6 @@ restore_flush:
clear_opt(sbi, FLUSH_MERGE);
f2fs_destroy_flush_cmd_control(sbi, false);
}
restore_ckpt:
if (need_restart_ckpt) {
if (f2fs_start_ckpt_thread(sbi))
f2fs_warn(sbi, "background ckpt thread has stopped");
} else if (need_stop_ckpt) {
f2fs_stop_ckpt_thread(sbi);
}
restore_gc:
if (need_restart_gc) {
if (f2fs_start_gc_thread(sbi))