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GFS2: Clean up log flush header writing 

We already send both a pre and post flush to the block device
when writing a journal header. There is no need to wait for
the previous I/O specifically when we do this, unless we've
turned "barriers" off.

As a side effect, this also cleans up the code path for flushing
the journal and makes it more readable.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This commit is contained in:
Steven Whitehouse 2012-03-09 10:45:56 +00:00
parent 75ca61c101
commit 34cc1781c2
1 changed files with 66 additions and 65 deletions
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131
fs/gfs2/log.c
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@ -491,66 +491,8 @@ static void log_pull_tail(struct gfs2_sbd *sdp, unsigned int new_tail)
sdp->sd_log_tail = new_tail;
}
/**
* log_write_header - Get and initialize a journal header buffer
* @sdp: The GFS2 superblock
*
* Returns: the initialized log buffer descriptor
*/
static void log_write_header(struct gfs2_sbd *sdp, u32 flags, int pull)
{
u64 blkno = gfs2_log_bmap(sdp, sdp->sd_log_flush_head);
struct buffer_head *bh;
struct gfs2_log_header *lh;
unsigned int tail;
u32 hash;
bh = sb_getblk(sdp->sd_vfs, blkno);
lock_buffer(bh);
memset(bh->b_data, 0, bh->b_size);
set_buffer_uptodate(bh);
clear_buffer_dirty(bh);
gfs2_ail1_empty(sdp);
tail = current_tail(sdp);
lh = (struct gfs2_log_header *)bh->b_data;
memset(lh, 0, sizeof(struct gfs2_log_header));
lh->lh_header.mh_magic = cpu_to_be32(GFS2_MAGIC);
lh->lh_header.mh_type = cpu_to_be32(GFS2_METATYPE_LH);
lh->lh_header.__pad0 = cpu_to_be64(0);
lh->lh_header.mh_format = cpu_to_be32(GFS2_FORMAT_LH);
lh->lh_header.mh_jid = cpu_to_be32(sdp->sd_jdesc->jd_jid);
lh->lh_sequence = cpu_to_be64(sdp->sd_log_sequence++);
lh->lh_flags = cpu_to_be32(flags);
lh->lh_tail = cpu_to_be32(tail);
lh->lh_blkno = cpu_to_be32(sdp->sd_log_flush_head);
hash = gfs2_disk_hash(bh->b_data, sizeof(struct gfs2_log_header));
lh->lh_hash = cpu_to_be32(hash);
bh->b_end_io = end_buffer_write_sync;
get_bh(bh);
if (test_bit(SDF_NOBARRIERS, &sdp->sd_flags))
submit_bh(WRITE_SYNC | REQ_META | REQ_PRIO, bh);
else
submit_bh(WRITE_FLUSH_FUA | REQ_META, bh);
wait_on_buffer(bh);
if (!buffer_uptodate(bh))
gfs2_io_error_bh(sdp, bh);
brelse(bh);
if (sdp->sd_log_tail != tail)
log_pull_tail(sdp, tail);
else
gfs2_assert_withdraw(sdp, !pull);
sdp->sd_log_idle = (tail == sdp->sd_log_flush_head);
gfs2_log_incr_head(sdp);
}
static void log_flush_commit(struct gfs2_sbd *sdp)
static void log_flush_wait(struct gfs2_sbd *sdp)
{
DEFINE_WAIT(wait);
@ -563,8 +505,6 @@ static void log_flush_commit(struct gfs2_sbd *sdp)
} while(atomic_read(&sdp->sd_log_in_flight));
finish_wait(&sdp->sd_log_flush_wait, &wait);
}
log_write_header(sdp, 0, 0);
}
static int bd_cmp(void *priv, struct list_head *a, struct list_head *b)
@ -633,6 +573,68 @@ static void gfs2_ordered_wait(struct gfs2_sbd *sdp)
gfs2_log_unlock(sdp);
}
/**
* log_write_header - Get and initialize a journal header buffer
* @sdp: The GFS2 superblock
*
* Returns: the initialized log buffer descriptor
*/
static void log_write_header(struct gfs2_sbd *sdp, u32 flags, int pull)
{
u64 blkno = gfs2_log_bmap(sdp, sdp->sd_log_flush_head);
struct buffer_head *bh;
struct gfs2_log_header *lh;
unsigned int tail;
u32 hash;
bh = sb_getblk(sdp->sd_vfs, blkno);
lock_buffer(bh);
memset(bh->b_data, 0, bh->b_size);
set_buffer_uptodate(bh);
clear_buffer_dirty(bh);
gfs2_ail1_empty(sdp);
tail = current_tail(sdp);
lh = (struct gfs2_log_header *)bh->b_data;
memset(lh, 0, sizeof(struct gfs2_log_header));
lh->lh_header.mh_magic = cpu_to_be32(GFS2_MAGIC);
lh->lh_header.mh_type = cpu_to_be32(GFS2_METATYPE_LH);
lh->lh_header.__pad0 = cpu_to_be64(0);
lh->lh_header.mh_format = cpu_to_be32(GFS2_FORMAT_LH);
lh->lh_header.mh_jid = cpu_to_be32(sdp->sd_jdesc->jd_jid);
lh->lh_sequence = cpu_to_be64(sdp->sd_log_sequence++);
lh->lh_flags = cpu_to_be32(flags);
lh->lh_tail = cpu_to_be32(tail);
lh->lh_blkno = cpu_to_be32(sdp->sd_log_flush_head);
hash = gfs2_disk_hash(bh->b_data, sizeof(struct gfs2_log_header));
lh->lh_hash = cpu_to_be32(hash);
bh->b_end_io = end_buffer_write_sync;
get_bh(bh);
if (test_bit(SDF_NOBARRIERS, &sdp->sd_flags)) {
gfs2_ordered_wait(sdp);
log_flush_wait(sdp);
submit_bh(WRITE_SYNC | REQ_META | REQ_PRIO, bh);
} else {
submit_bh(WRITE_FLUSH_FUA | REQ_META, bh);
}
wait_on_buffer(bh);
if (!buffer_uptodate(bh))
gfs2_io_error_bh(sdp, bh);
brelse(bh);
if (sdp->sd_log_tail != tail)
log_pull_tail(sdp, tail);
else
gfs2_assert_withdraw(sdp, !pull);
sdp->sd_log_idle = (tail == sdp->sd_log_flush_head);
gfs2_log_incr_head(sdp);
}
/**
* gfs2_log_flush - flush incore transaction(s)
* @sdp: the filesystem
@ -676,11 +678,10 @@ void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl)
gfs2_ordered_write(sdp);
lops_before_commit(sdp);
gfs2_ordered_wait(sdp);
if (sdp->sd_log_head != sdp->sd_log_flush_head)
log_flush_commit(sdp);
else if (sdp->sd_log_tail != current_tail(sdp) && !sdp->sd_log_idle){
if (sdp->sd_log_head != sdp->sd_log_flush_head) {
log_write_header(sdp, 0, 0);
} else if (sdp->sd_log_tail != current_tail(sdp) && !sdp->sd_log_idle){
gfs2_log_lock(sdp);
atomic_dec(&sdp->sd_log_blks_free); /* Adjust for unreserved buffer */
trace_gfs2_log_blocks(sdp, -1);