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Commit 17bd55d0 authored by Eric Sandeen's avatar Eric Sandeen Committed by Theodore Ts'o
Browse files

fs-writeback: Add helper function to start writeback if idle 



ext4, at least, would like to start pushing on writeback if it starts
to get close to ENOSPC when reserving worst-case blocks for delalloc
writes.  Writing out delalloc data will convert those worst-case
predictions into usually smaller actual usage, freeing up space
before we hit ENOSPC based on this speculation.

Thanks to Jens for the suggestion for the helper function,
& the naming help.

I've made the helper return status on whether writeback was
started even though I don't plan to use it in the ext4 patch;
it seems like it would be potentially useful to test this
in some cases.

Signed-off-by: default avatarEric Sandeen <sandeen@redhat.com>
Acked-by: default avatarJan Kara <jack@suse.cz>
parent d3533d72

fs/fs-writeback.c

+17 −0
Original line number Diff line number Diff line
@@ -1186,6 +1186,23 @@ void writeback_inodes_sb(struct super_block *sb) 
}

EXPORT_SYMBOL(writeback_inodes_sb);



/**

 * writeback_inodes_sb_if_idle	-	start writeback if none underway

 * @sb: the superblock

 *

 * Invoke writeback_inodes_sb if no writeback is currently underway.

 * Returns 1 if writeback was started, 0 if not.

 */

int writeback_inodes_sb_if_idle(struct super_block *sb)

{

	if (!writeback_in_progress(sb->s_bdi)) {

		writeback_inodes_sb(sb);

		return 1;

	} else

		return 0;

}

EXPORT_SYMBOL(writeback_inodes_sb_if_idle);



/**

 * sync_inodes_sb	-	sync sb inode pages

 * @sb: the superblock

include/linux/writeback.h

+1 −0
Original line number Diff line number Diff line
@@ -70,6 +70,7 @@ struct writeback_control { 
struct bdi_writeback;

int inode_wait(void *);

void writeback_inodes_sb(struct super_block *);

int writeback_inodes_sb_if_idle(struct super_block *);

void sync_inodes_sb(struct super_block *);

void writeback_inodes_wbc(struct writeback_control *wbc);

long wb_do_writeback(struct bdi_writeback *wb, int force_wait);