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author | Jens Axboe <jens.axboe@oracle.com> | 2009-09-24 15:25:11 +0200 |
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committer | Jens Axboe <jens.axboe@oracle.com> | 2009-09-25 18:08:26 +0200 |
commit | 9ecc2738ac2371f88dff5d48914b4e35c45203cd (patch) | |
tree | 12cd500172561fb43e5cbe1ee1993945a4ac2c5c /fs | |
parent | cf137307cd9827495b65e7d74ea2b610daa9898b (diff) | |
download | linux-stable-9ecc2738ac2371f88dff5d48914b4e35c45203cd.tar.gz linux-stable-9ecc2738ac2371f88dff5d48914b4e35c45203cd.tar.bz2 linux-stable-9ecc2738ac2371f88dff5d48914b4e35c45203cd.zip |
writeback: make the super_block pinning more efficient
Currently we pin the inode->i_sb for every single inode. This
increases cache traffic on sb->s_umount sem. Lets instead
cache the inode sb pin state and keep the super_block pinned
for as long as keep writing out inodes from the same
super_block.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'fs')
-rw-r--r-- | fs/fs-writeback.c | 46 |
1 files changed, 29 insertions, 17 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 225c7316344e..c6bf775e641a 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -540,6 +540,17 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) return ret; } +static void unpin_sb_for_writeback(struct super_block **psb) +{ + struct super_block *sb = *psb; + + if (sb) { + up_read(&sb->s_umount); + put_super(sb); + *psb = NULL; + } +} + /* * For WB_SYNC_NONE writeback, the caller does not have the sb pinned * before calling writeback. So make sure that we do pin it, so it doesn't @@ -549,11 +560,20 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) * 1 if we failed. */ static int pin_sb_for_writeback(struct writeback_control *wbc, - struct inode *inode) + struct inode *inode, struct super_block **psb) { struct super_block *sb = inode->i_sb; /* + * If this sb is already pinned, nothing more to do. If not and + * *psb is non-NULL, unpin the old one first + */ + if (sb == *psb) + return 0; + else if (*psb) + unpin_sb_for_writeback(psb); + + /* * Caller must already hold the ref for this */ if (wbc->sync_mode == WB_SYNC_ALL) { @@ -566,7 +586,7 @@ static int pin_sb_for_writeback(struct writeback_control *wbc, if (down_read_trylock(&sb->s_umount)) { if (sb->s_root) { spin_unlock(&sb_lock); - return 0; + goto pinned; } /* * umounted, drop rwsem again and fall through to failure @@ -577,24 +597,15 @@ static int pin_sb_for_writeback(struct writeback_control *wbc, sb->s_count--; spin_unlock(&sb_lock); return 1; -} - -static void unpin_sb_for_writeback(struct writeback_control *wbc, - struct inode *inode) -{ - struct super_block *sb = inode->i_sb; - - if (wbc->sync_mode == WB_SYNC_ALL) - return; - - up_read(&sb->s_umount); - put_super(sb); +pinned: + *psb = sb; + return 0; } static void writeback_inodes_wb(struct bdi_writeback *wb, struct writeback_control *wbc) { - struct super_block *sb = wbc->sb; + struct super_block *sb = wbc->sb, *pin_sb = NULL; const int is_blkdev_sb = sb_is_blkdev_sb(sb); const unsigned long start = jiffies; /* livelock avoidance */ @@ -653,7 +664,7 @@ static void writeback_inodes_wb(struct bdi_writeback *wb, if (inode_dirtied_after(inode, start)) break; - if (pin_sb_for_writeback(wbc, inode)) { + if (pin_sb_for_writeback(wbc, inode, &pin_sb)) { requeue_io(inode); continue; } @@ -662,7 +673,6 @@ static void writeback_inodes_wb(struct bdi_writeback *wb, __iget(inode); pages_skipped = wbc->pages_skipped; writeback_single_inode(inode, wbc); - unpin_sb_for_writeback(wbc, inode); if (wbc->pages_skipped != pages_skipped) { /* * writeback is not making progress due to locked @@ -682,6 +692,8 @@ static void writeback_inodes_wb(struct bdi_writeback *wb, wbc->more_io = 1; } + unpin_sb_for_writeback(&pin_sb); + spin_unlock(&inode_lock); /* Leave any unwritten inodes on b_io */ } |