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authorNeilBrown <neilb@suse.com>2017-03-15 06:05:13 +0300
committerShaohua Li <shli@fb.com>2017-03-23 05:16:56 +0300
commit0472a42ba1f89ec85f070c731f4440d7cc38c44c (patch)
treeabdcc017ea2f4fc66e80b2d5f99921894702b687 /drivers/md/raid5.c
parent016c76ac76e4c678b01a75a602dc6be0282f5b29 (diff)
downloadlinux-0472a42ba1f89ec85f070c731f4440d7cc38c44c.tar.xz
md/raid5: remove over-loading of ->bi_phys_segments.
When a read request, which bypassed the cache, fails, we need to retry it through the cache. This involves attaching it to a sequence of stripe_heads, and it may not be possible to get all the stripe_heads we need at once. We do what we can, and record how far we got in ->bi_phys_segments so we can pick up again later. There is only ever one bio which may have a non-zero offset stored in ->bi_phys_segments, the one that is either active in the single thread which calls retry_aligned_read(), or is in conf->retry_read_aligned waiting for retry_aligned_read() to be called again. So we only need to store one offset value. This can be in a local variable passed between remove_bio_from_retry() and retry_aligned_read(), or in the r5conf structure next to the ->retry_read_aligned pointer. Storing it there allows the last usage of ->bi_phys_segments to be removed from md/raid5.c. Signed-off-by: NeilBrown <neilb@suse.com> Signed-off-by: Shaohua Li <shli@fb.com>
Diffstat (limited to 'drivers/md/raid5.c')
-rw-r--r--drivers/md/raid5.c24
1 files changed, 12 insertions, 12 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 0ec9e0212158..1c8be667e9a9 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -5082,12 +5082,14 @@ static void add_bio_to_retry(struct bio *bi,struct r5conf *conf)
md_wakeup_thread(conf->mddev->thread);
}
-static struct bio *remove_bio_from_retry(struct r5conf *conf)
+static struct bio *remove_bio_from_retry(struct r5conf *conf,
+ unsigned int *offset)
{
struct bio *bi;
bi = conf->retry_read_aligned;
if (bi) {
+ *offset = conf->retry_read_offset;
conf->retry_read_aligned = NULL;
return bi;
}
@@ -5095,11 +5097,7 @@ static struct bio *remove_bio_from_retry(struct r5conf *conf)
if(bi) {
conf->retry_read_aligned_list = bi->bi_next;
bi->bi_next = NULL;
- /*
- * this sets the active strip count to 1 and the processed
- * strip count to zero (upper 8 bits)
- */
- raid5_set_bi_processed_stripes(bi, 0);
+ *offset = 0;
}
return bi;
@@ -6055,7 +6053,8 @@ static inline sector_t raid5_sync_request(struct mddev *mddev, sector_t sector_n
return STRIPE_SECTORS;
}
-static int retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
+static int retry_aligned_read(struct r5conf *conf, struct bio *raid_bio,
+ unsigned int offset)
{
/* We may not be able to submit a whole bio at once as there
* may not be enough stripe_heads available.
@@ -6084,7 +6083,7 @@ static int retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
sector += STRIPE_SECTORS,
scnt++) {
- if (scnt < raid5_bi_processed_stripes(raid_bio))
+ if (scnt < offset)
/* already done this stripe */
continue;
@@ -6092,15 +6091,15 @@ static int retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
if (!sh) {
/* failed to get a stripe - must wait */
- raid5_set_bi_processed_stripes(raid_bio, scnt);
conf->retry_read_aligned = raid_bio;
+ conf->retry_read_offset = scnt;
return handled;
}
if (!add_stripe_bio(sh, raid_bio, dd_idx, 0, 0)) {
raid5_release_stripe(sh);
- raid5_set_bi_processed_stripes(raid_bio, scnt);
conf->retry_read_aligned = raid_bio;
+ conf->retry_read_offset = scnt;
return handled;
}
@@ -6228,6 +6227,7 @@ static void raid5d(struct md_thread *thread)
while (1) {
struct bio *bio;
int batch_size, released;
+ unsigned int offset;
released = release_stripe_list(conf, conf->temp_inactive_list);
if (released)
@@ -6245,10 +6245,10 @@ static void raid5d(struct md_thread *thread)
}
raid5_activate_delayed(conf);
- while ((bio = remove_bio_from_retry(conf))) {
+ while ((bio = remove_bio_from_retry(conf, &offset))) {
int ok;
spin_unlock_irq(&conf->device_lock);
- ok = retry_aligned_read(conf, bio);
+ ok = retry_aligned_read(conf, bio, offset);
spin_lock_irq(&conf->device_lock);
if (!ok)
break;