| From 856bf4d717feb8c55d4e2f817b71ebb70cfbc67b Mon Sep 17 00:00:00 2001 |
| From: Nick Piggin <npiggin@suse.de> |
| Date: Tue, 6 Jan 2009 14:40:26 -0800 |
| Subject: fs: sys_sync fix |
| |
| From: Nick Piggin <npiggin@suse.de> |
| |
| commit 856bf4d717feb8c55d4e2f817b71ebb70cfbc67b upstream. |
| |
| s_syncing livelock avoidance was breaking data integrity guarantee of |
| sys_sync, by allowing sys_sync to skip writing or waiting for superblocks |
| if there is a concurrent sys_sync happening. |
| |
| This livelock avoidance is much less important now that we don't have the |
| get_super_to_sync() call after every sb that we sync. This was replaced |
| by __put_super_and_need_restart. |
| |
| Signed-off-by: Nick Piggin <npiggin@suse.de> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
| |
| --- |
| fs/fs-writeback.c | 20 +------------------- |
| include/linux/fs.h | 1 - |
| 2 files changed, 1 insertion(+), 20 deletions(-) |
| |
| --- a/fs/fs-writeback.c |
| +++ b/fs/fs-writeback.c |
| @@ -652,18 +652,6 @@ void sync_inodes_sb(struct super_block * |
| sync_sb_inodes(sb, &wbc); |
| } |
| |
| -/* |
| - * Rather lame livelock avoidance. |
| - */ |
| -static void set_sb_syncing(int val) |
| -{ |
| - struct super_block *sb; |
| - spin_lock(&sb_lock); |
| - list_for_each_entry_reverse(sb, &super_blocks, s_list) |
| - sb->s_syncing = val; |
| - spin_unlock(&sb_lock); |
| -} |
| - |
| /** |
| * sync_inodes - writes all inodes to disk |
| * @wait: wait for completion |
| @@ -690,9 +678,6 @@ static void __sync_inodes(int wait) |
| spin_lock(&sb_lock); |
| restart: |
| list_for_each_entry(sb, &super_blocks, s_list) { |
| - if (sb->s_syncing) |
| - continue; |
| - sb->s_syncing = 1; |
| sb->s_count++; |
| spin_unlock(&sb_lock); |
| down_read(&sb->s_umount); |
| @@ -710,13 +695,10 @@ restart: |
| |
| void sync_inodes(int wait) |
| { |
| - set_sb_syncing(0); |
| __sync_inodes(0); |
| |
| - if (wait) { |
| - set_sb_syncing(0); |
| + if (wait) |
| __sync_inodes(1); |
| - } |
| } |
| |
| /** |
| --- a/include/linux/fs.h |
| +++ b/include/linux/fs.h |
| @@ -1080,7 +1080,6 @@ struct super_block { |
| struct rw_semaphore s_umount; |
| struct mutex s_lock; |
| int s_count; |
| - int s_syncing; |
| int s_need_sync_fs; |
| atomic_t s_active; |
| #ifdef CONFIG_SECURITY |
