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author | 2005-06-23 00:09:54 -0700 | |
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committer | 2005-06-23 09:45:27 -0700 | |
commit | 618f06362ae3f60f95d7b0e666de25ee6ae35679 (patch) | |
tree | 4415b4e590913e16535704168ea74c6af5a93c48 /fs/super.c | |
parent | [PATCH] Software suspend and recalc sigpending bug fix (diff) | |
download | linux-618f06362ae3f60f95d7b0e666de25ee6ae35679.tar.gz linux-618f06362ae3f60f95d7b0e666de25ee6ae35679.tar.bz2 linux-618f06362ae3f60f95d7b0e666de25ee6ae35679.zip |
[PATCH] O(1) sb list traversing on syncs
This patch removes O(n^2) super block loops in sync_inodes(),
sync_filesystems() etc. in favour of using __put_super_and_need_restart()
which I introduced earlier. We faced a noticably long freezes on sb
syncing when there are thousands of super blocks in the system.
Signed-Off-By: Kirill Korotaev <dev@sw.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs/super.c')
-rw-r--r-- | fs/super.c | 83 |
1 files changed, 45 insertions, 38 deletions
diff --git a/fs/super.c b/fs/super.c index 573bcc81bb82..25bc1ec6bc5d 100644 --- a/fs/super.c +++ b/fs/super.c @@ -341,20 +341,22 @@ static inline void write_super(struct super_block *sb) */ void sync_supers(void) { - struct super_block * sb; -restart: + struct super_block *sb; + spin_lock(&sb_lock); - sb = sb_entry(super_blocks.next); - while (sb != sb_entry(&super_blocks)) +restart: + list_for_each_entry(sb, &super_blocks, s_list) { if (sb->s_dirt) { sb->s_count++; spin_unlock(&sb_lock); down_read(&sb->s_umount); write_super(sb); - drop_super(sb); - goto restart; - } else - sb = sb_entry(sb->s_list.next); + up_read(&sb->s_umount); + spin_lock(&sb_lock); + if (__put_super_and_need_restart(sb)) + goto restart; + } + } spin_unlock(&sb_lock); } @@ -381,20 +383,16 @@ void sync_filesystems(int wait) down(&mutex); /* Could be down_interruptible */ spin_lock(&sb_lock); - for (sb = sb_entry(super_blocks.next); sb != sb_entry(&super_blocks); - sb = sb_entry(sb->s_list.next)) { + list_for_each_entry(sb, &super_blocks, s_list) { if (!sb->s_op->sync_fs) continue; if (sb->s_flags & MS_RDONLY) continue; sb->s_need_sync_fs = 1; } - spin_unlock(&sb_lock); restart: - spin_lock(&sb_lock); - for (sb = sb_entry(super_blocks.next); sb != sb_entry(&super_blocks); - sb = sb_entry(sb->s_list.next)) { + list_for_each_entry(sb, &super_blocks, s_list) { if (!sb->s_need_sync_fs) continue; sb->s_need_sync_fs = 0; @@ -405,8 +403,11 @@ restart: down_read(&sb->s_umount); if (sb->s_root && (wait || sb->s_dirt)) sb->s_op->sync_fs(sb, wait); - drop_super(sb); - goto restart; + up_read(&sb->s_umount); + /* restart only when sb is no longer on the list */ + spin_lock(&sb_lock); + if (__put_super_and_need_restart(sb)) + goto restart; } spin_unlock(&sb_lock); up(&mutex); @@ -422,21 +423,25 @@ restart: struct super_block * get_super(struct block_device *bdev) { - struct list_head *p; + struct super_block *sb; + if (!bdev) return NULL; -rescan: + spin_lock(&sb_lock); - list_for_each(p, &super_blocks) { - struct super_block *s = sb_entry(p); - if (s->s_bdev == bdev) { - s->s_count++; +rescan: + list_for_each_entry(sb, &super_blocks, s_list) { + if (sb->s_bdev == bdev) { + sb->s_count++; spin_unlock(&sb_lock); - down_read(&s->s_umount); - if (s->s_root) - return s; - drop_super(s); - goto rescan; + down_read(&sb->s_umount); + if (sb->s_root) + return sb; + up_read(&sb->s_umount); + /* restart only when sb is no longer on the list */ + spin_lock(&sb_lock); + if (__put_super_and_need_restart(sb)) + goto rescan; } } spin_unlock(&sb_lock); @@ -447,20 +452,22 @@ EXPORT_SYMBOL(get_super); struct super_block * user_get_super(dev_t dev) { - struct list_head *p; + struct super_block *sb; -rescan: spin_lock(&sb_lock); - list_for_each(p, &super_blocks) { - struct super_block *s = sb_entry(p); - if (s->s_dev == dev) { - s->s_count++; +rescan: + list_for_each_entry(sb, &super_blocks, s_list) { + if (sb->s_dev == dev) { + sb->s_count++; spin_unlock(&sb_lock); - down_read(&s->s_umount); - if (s->s_root) - return s; - drop_super(s); - goto rescan; + down_read(&sb->s_umount); + if (sb->s_root) + return sb; + up_read(&sb->s_umount); + /* restart only when sb is no longer on the list */ + spin_lock(&sb_lock); + if (__put_super_and_need_restart(sb)) + goto rescan; } } spin_unlock(&sb_lock); |