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nilfs2: add missing blkdev_issue_flush() to nilfs_sync_fs()

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Under normal circumstances nilfs_sync_fs() writes out the super block,
which causes a flush of the underlying block device.  But this depends
on the THE_NILFS_SB_DIRTY flag, which is only set if the pointer to the
last segment crosses a segment boundary.  So if only a small amount of
data is written before the call to nilfs_sync_fs(), no flush of the
block device occurs.

In the above case an additional call to blkdev_issue_flush() is needed.
To prevent unnecessary overhead, the new flag nilfs->ns_flushed_device
is introduced, which is cleared whenever new logs are written and set
whenever the block device is flushed.  For convenience the function
nilfs_flush_device() is added, which contains the above logic.

Signed-off-by: Andreas Rohner <andreas.rohner@gmx.net>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andreas Rohner
2014-10-13 15:53:20 -07:00
committed by Linus Torvalds
parent 0f2a84f41a
commit e2c7617ae3
5 changed files with 37 additions and 10 deletions
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22
fs/nilfs2/the_nilfs.h
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@@ -46,6 +46,7 @@ enum {
/**
* struct the_nilfs - struct to supervise multiple nilfs mount points
* @ns_flags: flags
* @ns_flushed_device: flag indicating if all volatile data was flushed
* @ns_bdev: block device
* @ns_sem: semaphore for shared states
* @ns_snapshot_mount_mutex: mutex to protect snapshot mounts
@@ -103,6 +104,7 @@ enum {
*/
struct the_nilfs {
unsigned long ns_flags;
int ns_flushed_device;
struct block_device *ns_bdev;
struct rw_semaphore ns_sem;
@@ -371,4 +373,24 @@ static inline int nilfs_segment_is_active(struct the_nilfs *nilfs, __u64 n)
return n == nilfs->ns_segnum || n == nilfs->ns_nextnum;
}
static inline int nilfs_flush_device(struct the_nilfs *nilfs)
{
int err;
if (!nilfs_test_opt(nilfs, BARRIER) || nilfs->ns_flushed_device)
return 0;
nilfs->ns_flushed_device = 1;
/*
* the store to ns_flushed_device must not be reordered after
* blkdev_issue_flush().
*/
smp_wmb();
err = blkdev_issue_flush(nilfs->ns_bdev, GFP_KERNEL, NULL);
if (err != -EIO)
err = 0;
return err;
}
#endif /* _THE_NILFS_H */