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author | Jaegeuk Kim <jaegeuk@kernel.org> | 2021-07-22 19:30:58 +0200 |
---|---|---|
committer | Jaegeuk Kim <jaegeuk@kernel.org> | 2021-07-25 17:42:38 +0200 |
commit | 2eeb0dce728a7eac3e4dfe355d98af40d61f7a26 (patch) | |
tree | 1664feb29229d482c2c33001430724b2ec866b69 /fs/f2fs/node.c | |
parent | f2fs: remove allow_outplace_dio() (diff) | |
download | linux-2eeb0dce728a7eac3e4dfe355d98af40d61f7a26.tar.xz linux-2eeb0dce728a7eac3e4dfe355d98af40d61f7a26.zip |
f2fs: don't sleep while grabing nat_tree_lock
This tries to fix priority inversion in the below condition resulting in
long checkpoint delay.
f2fs_get_node_info()
- nat_tree_lock
-> sleep to grab journal_rwsem by contention
checkpoint
- waiting for nat_tree_lock
In order to let checkpoint go, let's release nat_tree_lock, if there's a
journal_rwsem contention.
Signed-off-by: Daeho Jeong <daehojeong@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Diffstat (limited to 'fs/f2fs/node.c')
-rw-r--r-- | fs/f2fs/node.c | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c index 0be9e2d7120e..c945a9730f3c 100644 --- a/fs/f2fs/node.c +++ b/fs/f2fs/node.c @@ -552,7 +552,7 @@ int f2fs_get_node_info(struct f2fs_sb_info *sbi, nid_t nid, int i; ni->nid = nid; - +retry: /* Check nat cache */ down_read(&nm_i->nat_tree_lock); e = __lookup_nat_cache(nm_i, nid); @@ -564,10 +564,19 @@ int f2fs_get_node_info(struct f2fs_sb_info *sbi, nid_t nid, return 0; } - memset(&ne, 0, sizeof(struct f2fs_nat_entry)); + /* + * Check current segment summary by trying to grab journal_rwsem first. + * This sem is on the critical path on the checkpoint requiring the above + * nat_tree_lock. Therefore, we should retry, if we failed to grab here + * while not bothering checkpoint. + */ + if (!rwsem_is_locked(&sbi->cp_global_sem)) { + down_read(&curseg->journal_rwsem); + } else if (!down_read_trylock(&curseg->journal_rwsem)) { + up_read(&nm_i->nat_tree_lock); + goto retry; + } - /* Check current segment summary */ - down_read(&curseg->journal_rwsem); i = f2fs_lookup_journal_in_cursum(journal, NAT_JOURNAL, nid, 0); if (i >= 0) { ne = nat_in_journal(journal, i); |