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Commit e5004753 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Al Viro
Browse files

cleanup sync_supers 



Merge the write_super helper into sync_super and move the check for
->write_super earlier so that we can avoid grabbing a reference to
a superblock that doesn't have it.

While we're at it also add a little comment documenting sync_supers.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent f3da392e

fs/super.c

+15 −12
Original line number Diff line number Diff line
@@ -399,16 +399,14 @@ void drop_super(struct super_block *sb) 


EXPORT_SYMBOL(drop_super);



static inline void write_super(struct super_block *sb)

{

	lock_super(sb);

	if (sb->s_root && sb->s_dirt)

		if (sb->s_op->write_super)

			sb->s_op->write_super(sb);

	unlock_super(sb);

}



/*

/**

 * sync_supers - helper for periodic superblock writeback

 *

 * Call the write_super method if present on all dirty superblocks in

 * the system.  This is for the periodic writeback used by most older

 * filesystems.  For data integrity superblock writeback use

 * sync_filesystems() instead.

 *

 * Note: check the dirty flag before waiting, so we don't

 * hold up the sync while mounting a device. (The newly

 * mounted device won't need syncing.)
@@ -420,12 +418,17 @@ void sync_supers(void) 
	spin_lock(&sb_lock);

restart:

	list_for_each_entry(sb, &super_blocks, s_list) {

		if (sb->s_dirt) {

		if (sb->s_op->write_super && sb->s_dirt) {

			sb->s_count++;

			spin_unlock(&sb_lock);



			down_read(&sb->s_umount);

			write_super(sb);

			lock_super(sb);

			if (sb->s_root && sb->s_dirt)

				sb->s_op->write_super(sb);

			unlock_super(sb);

			up_read(&sb->s_umount);



			spin_lock(&sb_lock);

			if (__put_super_and_need_restart(sb))

				goto restart;