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Add new functions for triggering inode writeback

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When btrfs is running low on metadata space, it needs to force delayed
allocation pages to disk.  It currently does this with a suboptimal walk
of a private list of inodes with delayed allocation, and it would be
much better if we used the generic flusher threads.

writeback_inodes_sb_if_idle would be ideal, but it waits for the flusher
thread to start IO on all the dirty pages in the FS before it returns.
This adds variants of writeback_inodes_sb* that allow the caller to
control how many pages get sent down.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason 2010-10-29 11:16:17 -04:00
parent cb44921a09
commit 3259f8bed2
2 changed files with 44 additions and 10 deletions
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52
fs/fs-writeback.c
View file

@ -1069,33 +1069,44 @@ static void wait_sb_inodes(struct super_block *sb)
}
/**
* writeback_inodes_sb - writeback dirty inodes from given super_block
* writeback_inodes_sb_nr - writeback dirty inodes from given super_block
* @sb: the superblock
* @nr: the number of pages to write
*
* Start writeback on some inodes on this super_block. No guarantees are made
* on how many (if any) will be written, and this function does not wait
* for IO completion of submitted IO. The number of pages submitted is
* returned.
* for IO completion of submitted IO.
*/
void writeback_inodes_sb(struct super_block *sb)
void writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr)
{
unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY);
unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS);
DECLARE_COMPLETION_ONSTACK(done);
struct wb_writeback_work work = {
.sb = sb,
.sync_mode = WB_SYNC_NONE,
.done = &done,
.nr_pages = nr,
};
WARN_ON(!rwsem_is_locked(&sb->s_umount));
work.nr_pages = nr_dirty + nr_unstable +
(inodes_stat.nr_inodes - inodes_stat.nr_unused);
bdi_queue_work(sb->s_bdi, &work);
wait_for_completion(&done);
}
EXPORT_SYMBOL(writeback_inodes_sb_nr);
/**
* writeback_inodes_sb - writeback dirty inodes from given super_block
* @sb: the superblock
*
* Start writeback on some inodes on this super_block. No guarantees are made
* on how many (if any) will be written, and this function does not wait
* for IO completion of submitted IO.
*/
void writeback_inodes_sb(struct super_block *sb)
{
return writeback_inodes_sb_nr(sb, global_page_state(NR_FILE_DIRTY) +
global_page_state(NR_UNSTABLE_NFS) +
(inodes_stat.nr_inodes - inodes_stat.nr_unused));
}
EXPORT_SYMBOL(writeback_inodes_sb);
/**
@ -1117,6 +1128,27 @@ int writeback_inodes_sb_if_idle(struct super_block *sb)
}
EXPORT_SYMBOL(writeback_inodes_sb_if_idle);
/**
* writeback_inodes_sb_if_idle - start writeback if none underway
* @sb: the superblock
* @nr: the number of pages to write
*
* Invoke writeback_inodes_sb if no writeback is currently underway.
* Returns 1 if writeback was started, 0 if not.
*/
int writeback_inodes_sb_nr_if_idle(struct super_block *sb,
unsigned long nr)
{
if (!writeback_in_progress(sb->s_bdi)) {
down_read(&sb->s_umount);
writeback_inodes_sb_nr(sb, nr);
up_read(&sb->s_umount);
return 1;
} else
return 0;
}
EXPORT_SYMBOL(writeback_inodes_sb_nr_if_idle);
/**
* sync_inodes_sb - sync sb inode pages
* @sb: the superblock

2
include/linux/writeback.h
View file

@ -60,7 +60,9 @@ struct writeback_control {
struct bdi_writeback;
int inode_wait(void *);
void writeback_inodes_sb(struct super_block *);
void writeback_inodes_sb_nr(struct super_block *, unsigned long nr);
int writeback_inodes_sb_if_idle(struct super_block *);
int writeback_inodes_sb_nr_if_idle(struct super_block *, unsigned long nr);
void sync_inodes_sb(struct super_block *);
void writeback_inodes_wb(struct bdi_writeback *wb,
struct writeback_control *wbc);