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[GFS2] Clean up journaled data writing
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This patch cleans up the code for writing journaled data into the log.
It also removes the need to allocate a small "tag" structure for each
block written into the log. Instead we just keep count of the outstanding
I/O so that we can be sure that its all been written at the correct time.
Another result of this patch is that a number of ll_rw_block() calls
have become submit_bh() calls, closing some races at the same time.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
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Steven Whitehouse committed Oct 10, 2007
1 parent 55c0c4a commit 16615be
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Showing 10 changed files with 269 additions and 220 deletions.
9 changes: 2 additions & 7 deletions fs/gfs2/incore.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -341,12 +341,6 @@ struct gfs2_quota_data {
unsigned long qd_last_touched;
};

struct gfs2_log_buf {
struct list_head lb_list;
struct buffer_head *lb_bh;
struct buffer_head *lb_real;
};

struct gfs2_trans {
unsigned long tr_ip;

Expand Down Expand Up @@ -631,7 +625,8 @@ struct gfs2_sbd {

unsigned long sd_log_flush_time;
struct rw_semaphore sd_log_flush_lock;
struct list_head sd_log_flush_list;
atomic_t sd_log_in_flight;
wait_queue_head_t sd_log_flush_wait;

unsigned int sd_log_flush_head;
u64 sd_log_flush_wrapped;
Expand Down
145 changes: 83 additions & 62 deletions fs/gfs2/log.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -104,11 +104,8 @@ static void gfs2_ail1_start_one(struct gfs2_sbd *sdp, struct gfs2_ail *ai)
gfs2_assert(sdp, bd->bd_ail == ai);

if (!buffer_busy(bh)) {
if (!buffer_uptodate(bh)) {
gfs2_log_unlock(sdp);
if (!buffer_uptodate(bh))
gfs2_io_error_bh(sdp, bh);
gfs2_log_lock(sdp);
}
list_move(&bd->bd_ail_st_list, &ai->ai_ail2_list);
continue;
}
Expand All @@ -118,9 +115,16 @@ static void gfs2_ail1_start_one(struct gfs2_sbd *sdp, struct gfs2_ail *ai)

list_move(&bd->bd_ail_st_list, &ai->ai_ail1_list);

get_bh(bh);
gfs2_log_unlock(sdp);
wait_on_buffer(bh);
ll_rw_block(WRITE, 1, &bh);
lock_buffer(bh);
if (test_clear_buffer_dirty(bh)) {
bh->b_end_io = end_buffer_write_sync;
submit_bh(WRITE, bh);
} else {
unlock_buffer(bh);
brelse(bh);
}
gfs2_log_lock(sdp);

retry = 1;
Expand Down Expand Up @@ -446,17 +450,34 @@ static unsigned int current_tail(struct gfs2_sbd *sdp)
return tail;
}

static inline void log_incr_head(struct gfs2_sbd *sdp)
void gfs2_log_incr_head(struct gfs2_sbd *sdp)
{
if (sdp->sd_log_flush_head == sdp->sd_log_tail)
gfs2_assert_withdraw(sdp, sdp->sd_log_flush_head == sdp->sd_log_head);
BUG_ON(sdp->sd_log_flush_head != sdp->sd_log_head);

if (++sdp->sd_log_flush_head == sdp->sd_jdesc->jd_blocks) {
sdp->sd_log_flush_head = 0;
sdp->sd_log_flush_wrapped = 1;
}
}

/**
* gfs2_log_write_endio - End of I/O for a log buffer
* @bh: The buffer head
* @uptodate: I/O Status
*
*/

static void gfs2_log_write_endio(struct buffer_head *bh, int uptodate)
{
struct gfs2_sbd *sdp = bh->b_private;
bh->b_private = NULL;

end_buffer_write_sync(bh, uptodate);
if (atomic_dec_and_test(&sdp->sd_log_in_flight))
wake_up(&sdp->sd_log_flush_wait);
}

/**
* gfs2_log_get_buf - Get and initialize a buffer to use for log control data
* @sdp: The GFS2 superblock
Expand All @@ -467,24 +488,41 @@ static inline void log_incr_head(struct gfs2_sbd *sdp)
struct buffer_head *gfs2_log_get_buf(struct gfs2_sbd *sdp)
{
u64 blkno = log_bmap(sdp, sdp->sd_log_flush_head);
struct gfs2_log_buf *lb;
struct buffer_head *bh;

lb = kzalloc(sizeof(struct gfs2_log_buf), GFP_NOFS | __GFP_NOFAIL);
list_add(&lb->lb_list, &sdp->sd_log_flush_list);

bh = lb->lb_bh = sb_getblk(sdp->sd_vfs, blkno);
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);
unlock_buffer(bh);

log_incr_head(sdp);
gfs2_log_incr_head(sdp);
atomic_inc(&sdp->sd_log_in_flight);
bh->b_private = sdp;
bh->b_end_io = gfs2_log_write_endio;

return bh;
}

/**
* gfs2_fake_write_endio -
* @bh: The buffer head
* @uptodate: The I/O Status
*
*/

static void gfs2_fake_write_endio(struct buffer_head *bh, int uptodate)
{
struct buffer_head *real_bh = bh->b_private;
struct gfs2_sbd *sdp = GFS2_SB(real_bh->b_page->mapping->host);

end_buffer_write_sync(bh, uptodate);
free_buffer_head(bh);
unlock_buffer(real_bh);
brelse(real_bh);
if (atomic_dec_and_test(&sdp->sd_log_in_flight))
wake_up(&sdp->sd_log_flush_wait);
}

/**
* gfs2_log_fake_buf - Build a fake buffer head to write metadata buffer to log
* @sdp: the filesystem
Expand All @@ -497,22 +535,20 @@ struct buffer_head *gfs2_log_fake_buf(struct gfs2_sbd *sdp,
struct buffer_head *real)
{
u64 blkno = log_bmap(sdp, sdp->sd_log_flush_head);
struct gfs2_log_buf *lb;
struct buffer_head *bh;

lb = kzalloc(sizeof(struct gfs2_log_buf), GFP_NOFS | __GFP_NOFAIL);
list_add(&lb->lb_list, &sdp->sd_log_flush_list);
lb->lb_real = real;

bh = lb->lb_bh = alloc_buffer_head(GFP_NOFS | __GFP_NOFAIL);
bh = alloc_buffer_head(GFP_NOFS | __GFP_NOFAIL);
atomic_set(&bh->b_count, 1);
bh->b_state = (1 << BH_Mapped) | (1 << BH_Uptodate);
bh->b_state = (1 << BH_Mapped) | (1 << BH_Uptodate) | (1 << BH_Lock);
set_bh_page(bh, real->b_page, bh_offset(real));
bh->b_blocknr = blkno;
bh->b_size = sdp->sd_sb.sb_bsize;
bh->b_bdev = sdp->sd_vfs->s_bdev;
bh->b_private = real;
bh->b_end_io = gfs2_fake_write_endio;

log_incr_head(sdp);
gfs2_log_incr_head(sdp);
atomic_inc(&sdp->sd_log_in_flight);

return bh;
}
Expand Down Expand Up @@ -579,45 +615,24 @@ static void log_write_header(struct gfs2_sbd *sdp, u32 flags, int pull)
gfs2_assert_withdraw(sdp, !pull);

sdp->sd_log_idle = (tail == sdp->sd_log_flush_head);
log_incr_head(sdp);
gfs2_log_incr_head(sdp);
}

static void log_flush_commit(struct gfs2_sbd *sdp)
{
struct list_head *head = &sdp->sd_log_flush_list;
struct gfs2_log_buf *lb;
struct buffer_head *bh;
int flushcount = 0;

while (!list_empty(head)) {
lb = list_entry(head->next, struct gfs2_log_buf, lb_list);
list_del(&lb->lb_list);
bh = lb->lb_bh;

wait_on_buffer(bh);
if (!buffer_uptodate(bh))
gfs2_io_error_bh(sdp, bh);
if (lb->lb_real) {
while (atomic_read(&bh->b_count) != 1) /* Grrrr... */
schedule();
free_buffer_head(bh);
} else
brelse(bh);
kfree(lb);
flushcount++;
DEFINE_WAIT(wait);

if (atomic_read(&sdp->sd_log_in_flight)) {
do {
prepare_to_wait(&sdp->sd_log_flush_wait, &wait,
TASK_UNINTERRUPTIBLE);
if (atomic_read(&sdp->sd_log_in_flight))
io_schedule();
} while(atomic_read(&sdp->sd_log_in_flight));
finish_wait(&sdp->sd_log_flush_wait, &wait);
}

/* If nothing was journaled, the header is unplanned and unwanted. */
if (flushcount) {
log_write_header(sdp, 0, 0);
} else {
unsigned int tail;
tail = current_tail(sdp);

gfs2_ail1_empty(sdp, 0);
if (sdp->sd_log_tail != tail)
log_pull_tail(sdp, tail);
}
log_write_header(sdp, 0, 0);
}

static void gfs2_ordered_write(struct gfs2_sbd *sdp)
Expand Down Expand Up @@ -698,10 +713,16 @@ void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl)
INIT_LIST_HEAD(&ai->ai_ail1_list);
INIT_LIST_HEAD(&ai->ai_ail2_list);

gfs2_assert_withdraw(sdp,
sdp->sd_log_num_buf + sdp->sd_log_num_databuf ==
sdp->sd_log_commited_buf +
sdp->sd_log_commited_databuf);
if (sdp->sd_log_num_buf != sdp->sd_log_commited_buf) {
printk(KERN_INFO "GFS2: log buf %u %u\n", sdp->sd_log_num_buf,
sdp->sd_log_commited_buf);
gfs2_assert_withdraw(sdp, 0);
}
if (sdp->sd_log_num_databuf != sdp->sd_log_commited_databuf) {
printk(KERN_INFO "GFS2: log databuf %u %u\n",
sdp->sd_log_num_databuf, sdp->sd_log_commited_databuf);
gfs2_assert_withdraw(sdp, 0);
}
gfs2_assert_withdraw(sdp,
sdp->sd_log_num_revoke == sdp->sd_log_commited_revoke);

Expand All @@ -713,7 +734,7 @@ void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl)
lops_before_commit(sdp);
gfs2_ordered_wait(sdp);

if (!list_empty(&sdp->sd_log_flush_list))
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){
gfs2_log_lock(sdp);
Expand Down
1 change: 1 addition & 0 deletions fs/gfs2/log.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -52,6 +52,7 @@ int gfs2_ail1_empty(struct gfs2_sbd *sdp, int flags);

int gfs2_log_reserve(struct gfs2_sbd *sdp, unsigned int blks);
void gfs2_log_release(struct gfs2_sbd *sdp, unsigned int blks);
void gfs2_log_incr_head(struct gfs2_sbd *sdp);

struct buffer_head *gfs2_log_get_buf(struct gfs2_sbd *sdp);
struct buffer_head *gfs2_log_fake_buf(struct gfs2_sbd *sdp,
Expand Down
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