Commit 856bf4d7 authored by Nick Piggin's avatar Nick Piggin Committed by Linus Torvalds

fs: sys_sync fix

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: default avatarNick Piggin <npiggin@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 38f21977
......@@ -652,18 +652,6 @@ void sync_inodes_sb(struct super_block *sb, int wait)
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 @@ static void __sync_inodes(int wait)
void sync_inodes(int wait)
{
set_sb_syncing(0);
__sync_inodes(0);
if (wait) {
set_sb_syncing(0);
if (wait)
__sync_inodes(1);
}
}
/**
......
......@@ -1133,7 +1133,6 @@ 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
......
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