If we detect an overlap, we set a flag and wait for a wakeup.
When requests are handled, if the flag was set, we perform the
wakeup.
Note that the code currently in -mm is badly broken. With this
patch applied, it passes tests the use O_DIRECT to cause lots
of overlapping requests.
Signed-off-by: Neil Brown <neilb@xxxxxxxxxxxxxxx>
### Diffstat output
./drivers/md/raid5.c | 52 ++++++++++++++++++++++++++++++++---------
./drivers/md/raid6main.c | 54 +++++++++++++++++++++++++++++++++++--------
./include/linux/raid/raid5.h | 2 +
3 files changed, 87 insertions(+), 21 deletions(-)
diff ./drivers/md/raid5.c~current~ ./drivers/md/raid5.c
--- ./drivers/md/raid5.c~current~ 2005-02-07 13:34:09.000000000 +1100
+++ ./drivers/md/raid5.c 2005-02-07 13:34:23.000000000 +1100
@@ -49,7 +49,7 @@
* This macro is used to determine the 'next' bio in the list, given the sector
* of the current stripe+device
*/
-#define r5_next_bio(bio, sect) ( ( bio->bi_sector + (bio->bi_size>>9) < sect + STRIPE_SECTORS) ? bio->bi_next : NULL)
+#define r5_next_bio(bio, sect) ( ( (bio)->bi_sector + ((bio)->bi_size>>9) < sect + STRIPE_SECTORS) ? (bio)->bi_next : NULL)
/*
* The following can be used to debug the driver
*/
@@ -722,6 +722,10 @@ static void compute_parity(struct stripe
ptr[count++] = page_address(sh->dev[i].page);
chosen = sh->dev[i].towrite;
sh->dev[i].towrite = NULL;
+
+ if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
+ wake_up(&conf->wait_for_overlap);
+
if (sh->dev[i].written) BUG();
sh->dev[i].written = chosen;
check_xor();
@@ -734,6 +738,10 @@ static void compute_parity(struct stripe
if (i!=pd_idx && sh->dev[i].towrite) {
chosen = sh->dev[i].towrite;
sh->dev[i].towrite = NULL;
+
+ if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
+ wake_up(&conf->wait_for_overlap);
+
if (sh->dev[i].written) BUG();
sh->dev[i].written = chosen;
}
@@ -790,7 +798,7 @@ static void compute_parity(struct stripe
* toread/towrite point to the first in a chain.
* The bi_next chain must be in order.
*/
-static int add_stripe_bio (struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
+static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
{
struct bio **bip;
raid5_conf_t *conf = sh->raid_conf;
@@ -808,9 +816,12 @@ static int add_stripe_bio (struct stripe
bip = &sh->dev[dd_idx].toread;
while (*bip && (*bip)->bi_sector < bi->bi_sector) {
if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector)
- return 0; /* cannot add just now due to overlap */
+ goto overlap;
bip = & (*bip)->bi_next;
}
+ if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9))
+ goto overlap;
+
if (*bip && bi->bi_next && (*bip) != bi->bi_next)
BUG();
if (*bip)
@@ -825,7 +836,7 @@ static int add_stripe_bio (struct stripe
(unsigned long long)sh->sector, dd_idx);
if (forwrite) {
- /* check if page is coverred */
+ /* check if page is covered */
sector_t sector = sh->dev[dd_idx].sector;
for (bi=sh->dev[dd_idx].towrite;
sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
@@ -838,6 +849,12 @@ static int add_stripe_bio (struct stripe
set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
}
return 1;
+
+ overlap:
+ set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
+ spin_unlock_irq(&conf->device_lock);
+ spin_unlock(&sh->lock);
+ return 0;
}
@@ -898,6 +915,8 @@ static void handle_stripe(struct stripe_
spin_lock_irq(&conf->device_lock);
rbi = dev->toread;
dev->toread = NULL;
+ if (test_and_clear_bit(R5_Overlap, &dev->flags))
+ wake_up(&conf->wait_for_overlap);
spin_unlock_irq(&conf->device_lock);
while (rbi && rbi->bi_sector < dev->sector + STRIPE_SECTORS) {
copy_data(0, rbi, dev->page, dev->sector);
@@ -945,6 +964,9 @@ static void handle_stripe(struct stripe_
sh->dev[i].towrite = NULL;
if (bi) to_write--;
+ if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
+ wake_up(&conf->wait_for_overlap);
+
while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
clear_bit(BIO_UPTODATE, &bi->bi_flags);
@@ -973,6 +995,8 @@ static void handle_stripe(struct stripe_
if (!test_bit(R5_Insync, &sh->dev[i].flags)) {
bi = sh->dev[i].toread;
sh->dev[i].toread = NULL;
+ if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
+ wake_up(&conf->wait_for_overlap);
if (bi) to_read--;
while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
@@ -1400,6 +1424,7 @@ static int make_request (request_queue_t
if ( bio_data_dir(bi) == WRITE )
md_write_start(mddev);
for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
+ DEFINE_WAIT(w);
new_sector = raid5_compute_sector(logical_sector,
raid_disks, data_disks, &dd_idx, &pd_idx, conf);
@@ -1408,25 +1433,29 @@ static int make_request (request_queue_t
(unsigned long long)new_sector,
(unsigned long long)logical_sector);
+ prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
+
+ retry:
sh = get_active_stripe(conf, new_sector, pd_idx, (bi->bi_rw&RWA_MASK));
if (sh) {
-
- while (!add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK))) {
- /* add failed due to overlap. Flush everything
+ if (!add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK))) {
+ /* Add failed due to overlap. Flush everything
* and wait a while
- * FIXME - overlapping requests should be handled better
*/
raid5_unplug_device(mddev->queue);
- set_current_state(TASK_UNINTERRUPTIBLE);
- schedule_timeout(1);
+ release_stripe(sh);
+ schedule();
+ goto retry;
}
-
+ finish_wait(&conf->wait_for_overlap, &w);
raid5_plug_device(conf);
handle_stripe(sh);
release_stripe(sh);
+
} else {
/* cannot get stripe for read-ahead, just give-up */
clear_bit(BIO_UPTODATE, &bi->bi_flags);
+ finish_wait(&conf->wait_for_overlap, &w);
break;
}
@@ -1574,6 +1603,7 @@ static int run (mddev_t *mddev)
spin_lock_init(&conf->device_lock);
init_waitqueue_head(&conf->wait_for_stripe);
+ init_waitqueue_head(&conf->wait_for_overlap);
INIT_LIST_HEAD(&conf->handle_list);
INIT_LIST_HEAD(&conf->delayed_list);
INIT_LIST_HEAD(&conf->inactive_list);
diff ./drivers/md/raid6main.c~current~ ./drivers/md/raid6main.c
--- ./drivers/md/raid6main.c~current~ 2005-02-07 13:34:09.000000000 +1100
+++ ./drivers/md/raid6main.c 2005-02-07 13:34:23.000000000 +1100
@@ -54,7 +54,7 @@
* This macro is used to determine the 'next' bio in the list, given the sector
* of the current stripe+device
*/
-#define r5_next_bio(bio, sect) ( ( bio->bi_sector + (bio->bi_size>>9) < sect + STRIPE_SECTORS) ? bio->bi_next : NULL)
+#define r5_next_bio(bio, sect) ( ( (bio)->bi_sector + ((bio)->bi_size>>9) < sect + STRIPE_SECTORS) ? (bio)->bi_next : NULL)
/*
* The following can be used to debug the driver
*/
@@ -690,7 +690,7 @@ static void copy_data(int frombio, struc
if (len > 0 && page_offset + len > STRIPE_SIZE)
clen = STRIPE_SIZE - page_offset;
else clen = len;
-
+
if (clen > 0) {
char *ba = __bio_kmap_atomic(bio, i, KM_USER0);
if (frombio)
@@ -735,6 +735,10 @@ static void compute_parity(struct stripe
if ( i != pd_idx && i != qd_idx && sh->dev[i].towrite ) {
chosen = sh->dev[i].towrite;
sh->dev[i].towrite = NULL;
+
+ if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
+ wake_up(&conf->wait_for_overlap);
+
if (sh->dev[i].written) BUG();
sh->dev[i].written = chosen;
}
@@ -897,7 +901,7 @@ static void compute_block_2(struct strip
* toread/towrite point to the first in a chain.
* The bi_next chain must be in order.
*/
-static void add_stripe_bio (struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
+static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
{
struct bio **bip;
raid6_conf_t *conf = sh->raid_conf;
@@ -914,10 +918,13 @@ static void add_stripe_bio (struct strip
else
bip = &sh->dev[dd_idx].toread;
while (*bip && (*bip)->bi_sector < bi->bi_sector) {
- BUG_ON((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector);
- bip = & (*bip)->bi_next;
+ if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector)
+ goto overlap;
+ bip = &(*bip)->bi_next;
}
-/* FIXME do I need to worry about overlapping bion */
+ if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9))
+ goto overlap;
+
if (*bip && bi->bi_next && (*bip) != bi->bi_next)
BUG();
if (*bip)
@@ -932,7 +939,7 @@ static void add_stripe_bio (struct strip
(unsigned long long)sh->sector, dd_idx);
if (forwrite) {
- /* check if page is coverred */
+ /* check if page is covered */
sector_t sector = sh->dev[dd_idx].sector;
for (bi=sh->dev[dd_idx].towrite;
sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
@@ -944,6 +951,13 @@ static void add_stripe_bio (struct strip
if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
}
+ return 1;
+
+ overlap:
+ set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
+ spin_unlock_irq(&conf->device_lock);
+ spin_unlock(&sh->lock);
+ return 0;
}
@@ -1007,6 +1021,8 @@ static void handle_stripe(struct stripe_
spin_lock_irq(&conf->device_lock);
rbi = dev->toread;
dev->toread = NULL;
+ if (test_and_clear_bit(R5_Overlap, &dev->flags))
+ wake_up(&conf->wait_for_overlap);
spin_unlock_irq(&conf->device_lock);
while (rbi && rbi->bi_sector < dev->sector + STRIPE_SECTORS) {
copy_data(0, rbi, dev->page, dev->sector);
@@ -1056,6 +1072,9 @@ static void handle_stripe(struct stripe_
sh->dev[i].towrite = NULL;
if (bi) to_write--;
+ if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
+ wake_up(&conf->wait_for_overlap);
+
while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
clear_bit(BIO_UPTODATE, &bi->bi_flags);
@@ -1084,6 +1103,8 @@ static void handle_stripe(struct stripe_
if (!test_bit(R5_Insync, &sh->dev[i].flags)) {
bi = sh->dev[i].toread;
sh->dev[i].toread = NULL;
+ if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
+ wake_up(&conf->wait_for_overlap);
if (bi) to_read--;
while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){
struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
@@ -1563,6 +1584,7 @@ static int make_request (request_queue_t
if ( bio_data_dir(bi) == WRITE )
md_write_start(mddev);
for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
+ DEFINE_WAIT(w);
new_sector = raid6_compute_sector(logical_sector,
raid_disks, data_disks, &dd_idx, &pd_idx, conf);
@@ -1571,17 +1593,28 @@ static int make_request (request_queue_t
(unsigned long long)new_sector,
(unsigned long long)logical_sector);
+ prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
+
+ retry:
sh = get_active_stripe(conf, new_sector, pd_idx, (bi->bi_rw&RWA_MASK));
if (sh) {
-
- add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK));
-
+ if (!add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK))) {
+ /* Add failed due to overlap. Flush everything
+ * and wait a while
+ */
+ raid6_unplug_device(mddev->queue);
+ release_stripe(sh);
+ schedule();
+ goto retry;
+ }
+ finish_wait(&conf->wait_for_overlap, &w);
raid6_plug_device(conf);
handle_stripe(sh);
release_stripe(sh);
} else {
/* cannot get stripe for read-ahead, just give-up */
clear_bit(BIO_UPTODATE, &bi->bi_flags);
+ finish_wait(&conf->wait_for_overlap, &w);
break;
}
@@ -1729,6 +1762,7 @@ static int run (mddev_t *mddev)
spin_lock_init(&conf->device_lock);
init_waitqueue_head(&conf->wait_for_stripe);
+ init_waitqueue_head(&conf->wait_for_overlap);
INIT_LIST_HEAD(&conf->handle_list);
INIT_LIST_HEAD(&conf->delayed_list);
INIT_LIST_HEAD(&conf->inactive_list);
diff ./include/linux/raid/raid5.h~current~ ./include/linux/raid/raid5.h
--- ./include/linux/raid/raid5.h~current~ 2005-02-07 13:31:05.000000000 +1100
+++ ./include/linux/raid/raid5.h 2005-02-07 13:34:23.000000000 +1100
@@ -152,6 +152,7 @@ struct stripe_head {
#define R5_Wantread 4 /* want to schedule a read */
#define R5_Wantwrite 5
#define R5_Syncio 6 /* this io need to be accounted as resync io */
+#define R5_Overlap 7 /* There is a pending overlapping request on this block */
/*
* Write method
@@ -219,6 +220,7 @@ struct raid5_private_data {
atomic_t active_stripes;
struct list_head inactive_list;
wait_queue_head_t wait_for_stripe;
+ wait_queue_head_t wait_for_overlap;
int inactive_blocked; /* release of inactive stripes blocked,
* waiting for 25% to be free
*/
-
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