Make sure that not only sync_filesystem but all callers of writeback_inodes_sb
have the superblock protected against remount. As-is this disables all
functionality for these callers, but the next patch relies on this locking to
fix writeback_inodes_sb for sync_filesystem.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Index: linux-2.6/fs/fs-writeback.c
===================================================================
--- linux-2.6.orig/fs/fs-writeback.c 2010-06-08 16:25:35.000000000 +0200
+++ linux-2.6/fs/fs-writeback.c 2010-06-08 16:27:47.846255651 +0200
@@ -1180,6 +1180,8 @@ void writeback_inodes_sb(struct super_bl
.sync_mode = WB_SYNC_NONE,
};
+ WARN_ON(!rwsem_is_locked(&sb->s_umount));
+
args.nr_pages = nr_dirty + nr_unstable +
(inodes_stat.nr_inodes - inodes_stat.nr_unused);
@@ -1197,7 +1199,9 @@ EXPORT_SYMBOL(writeback_inodes_sb);
int writeback_inodes_sb_if_idle(struct super_block *sb)
{
if (!writeback_in_progress(sb->s_bdi)) {
+ down_read(&sb->s_umount);
writeback_inodes_sb(sb);
+ up_read(&sb->s_umount);
return 1;
} else
return 0;
@@ -1220,6 +1224,8 @@ void sync_inodes_sb(struct super_block *
.range_cyclic = 0,
};
+ WARN_ON(!rwsem_is_locked(&sb->s_umount));
+
bdi_queue_work_onstack(&args);
wait_sb_inodes(sb);
}
Index: linux-2.6/fs/ubifs/budget.c
===================================================================
--- linux-2.6.orig/fs/ubifs/budget.c 2010-06-08 16:22:16.000000000 +0200
+++ linux-2.6/fs/ubifs/budget.c 2010-06-08 16:26:50.464004778 +0200
@@ -62,7 +62,9 @@
*/
static void shrink_liability(struct ubifs_info *c, int nr_to_write)
{
+ down_read(&c->vfs_sb->s_umount);
writeback_inodes_sb(c->vfs_sb);
+ up_read(&c->vfs_sb->s_umount);
}
/**
--
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