diff options
| author | Jan Kara <jack@suse.cz> | 2009-09-16 19:22:48 +0200 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2009-09-25 18:08:24 +0200 |
| commit | a5989bdc981ec85e0734ac22519cc0b780813d7b (patch) | |
| tree | 74cc93bd420b7bd044e3fd5451c652b3742015e6 | |
| parent | 7fa07729e439a6184bd824746d06a49cca553f15 (diff) | |
fs: Fix busyloop in wb_writeback()
If all inodes are under writeback (e.g. in case when there's only one inode
with dirty pages), wb_writeback() with WB_SYNC_NONE work basically degrades
to busylooping until I_SYNC flags of the inode is cleared. Fix the problem by
waiting on I_SYNC flags of an inode on b_more_io list in case we failed to
write anything.
Tested-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
| -rw-r--r-- | fs/fs-writeback.c | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 8e1e5e19d21e..c59d6737036c 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -706,6 +706,7 @@ static long wb_writeback(struct bdi_writeback *wb, }; unsigned long oldest_jif; long wrote = 0; + struct inode *inode; if (wbc.for_kupdate) { wbc.older_than_this = &oldest_jif; @@ -747,8 +748,24 @@ static long wb_writeback(struct bdi_writeback *wb, * If we ran out of stuff to write, bail unless more_io got set */ if (wbc.nr_to_write > 0 || wbc.pages_skipped > 0) { - if (wbc.more_io && !wbc.for_kupdate) + if (wbc.more_io && !wbc.for_kupdate) { + if (wbc.nr_to_write < MAX_WRITEBACK_PAGES) + continue; + /* + * Nothing written. Wait for some inode to + * become available for writeback. Otherwise + * we'll just busyloop. + */ + spin_lock(&inode_lock); + if (!list_empty(&wb->b_more_io)) { + inode = list_entry( + wb->b_more_io.prev, + struct inode, i_list); + inode_wait_for_writeback(inode); + } + spin_unlock(&inode_lock); continue; + } break; } } |