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authorMiao Xie <miaox@cn.fujitsu.com>2013-01-10 13:47:57 +0800
committerFengguang Wu <fengguang.wu@intel.com>2013-01-12 10:47:43 +0800
commit10ee27a06cc8eb57f83342a8eabcb75deb872d52 (patch)
treed14f69011b7aa1896f1aef37cb2b64f868bce459 /fs/fs-writeback.c
parent9931faca02c604c22335f5a935a501bb2ace6e20 (diff)
vfs: re-implement writeback_inodes_sb(_nr)_if_idle() and rename them
writeback_inodes_sb(_nr)_if_idle() is re-implemented by replacing down_read() with down_read_trylock() because - If ->s_umount is write locked, then the sb is not idle. That is writeback_inodes_sb(_nr)_if_idle() needn't wait for the lock. - writeback_inodes_sb(_nr)_if_idle() grabs s_umount lock when it want to start writeback, it may bring us deadlock problem when doing umount. In order to fix the problem, ext4 and btrfs implemented their own writeback functions instead of writeback_inodes_sb(_nr)_if_idle(), but it introduced the redundant code, it is better to implement a new writeback_inodes_sb(_nr)_if_idle(). The name of these two functions is cumbersome, so rename them to try_to_writeback_inodes_sb(_nr). This idea came from Christoph Hellwig. Some code is from the patch of Kamal Mostafa. Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Diffstat (limited to 'fs/fs-writeback.c')
-rw-r--r--fs/fs-writeback.c44
1 files changed, 20 insertions, 24 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 310972b72a6..ad3cc46a743 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -1332,47 +1332,43 @@ void writeback_inodes_sb(struct super_block *sb, enum wb_reason reason)
EXPORT_SYMBOL(writeback_inodes_sb);
/**
- * writeback_inodes_sb_if_idle - start writeback if none underway
+ * try_to_writeback_inodes_sb_nr - try to start writeback if none underway
* @sb: the superblock
- * @reason: reason why some writeback work was initiated
+ * @nr: the number of pages to write
+ * @reason: the reason of writeback
*
- * Invoke writeback_inodes_sb if no writeback is currently underway.
+ * Invoke writeback_inodes_sb_nr 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, enum wb_reason reason)
+int try_to_writeback_inodes_sb_nr(struct super_block *sb,
+ unsigned long nr,
+ enum wb_reason reason)
{
- if (!writeback_in_progress(sb->s_bdi)) {
- down_read(&sb->s_umount);
- writeback_inodes_sb(sb, reason);
- up_read(&sb->s_umount);
+ if (writeback_in_progress(sb->s_bdi))
return 1;
- } else
+
+ if (!down_read_trylock(&sb->s_umount))
return 0;
+
+ writeback_inodes_sb_nr(sb, nr, reason);
+ up_read(&sb->s_umount);
+ return 1;
}
-EXPORT_SYMBOL(writeback_inodes_sb_if_idle);
+EXPORT_SYMBOL(try_to_writeback_inodes_sb_nr);
/**
- * writeback_inodes_sb_nr_if_idle - start writeback if none underway
+ * try_to_writeback_inodes_sb - try to start writeback if none underway
* @sb: the superblock
- * @nr: the number of pages to write
* @reason: reason why some writeback work was initiated
*
- * Invoke writeback_inodes_sb if no writeback is currently underway.
+ * Implement by try_to_writeback_inodes_sb_nr()
* Returns 1 if writeback was started, 0 if not.
*/
-int writeback_inodes_sb_nr_if_idle(struct super_block *sb,
- unsigned long nr,
- enum wb_reason reason)
+int try_to_writeback_inodes_sb(struct super_block *sb, enum wb_reason reason)
{
- if (!writeback_in_progress(sb->s_bdi)) {
- down_read(&sb->s_umount);
- writeback_inodes_sb_nr(sb, nr, reason);
- up_read(&sb->s_umount);
- return 1;
- } else
- return 0;
+ return try_to_writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason);
}
-EXPORT_SYMBOL(writeback_inodes_sb_nr_if_idle);
+EXPORT_SYMBOL(try_to_writeback_inodes_sb);
/**
* sync_inodes_sb - sync sb inode pages