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dm thin: requeue bios to DM core if no_free_space and in read-only mode 

Now that we switch the pool to read-only mode when the data device runs
out of space it causes active writers to get IO errors once we resume
after resizing the data device.

If no_free_space is set, save bios to the 'retry_on_resume_list' and
requeue them on resume (once the data or metadata device may have been
resized).

With this patch the resize_io test passes again (on slower storage):
 dmtest run --suite thin-provisioning -n /resize_io/

Later patches fix some subtle races associated with the pool mode
transitions done as part of the pool's -ENOSPC handling.  These races
are exposed on fast storage (e.g. PCIe SSD).

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Joe Thornber <ejt@redhat.com>
This commit is contained in:
Mike Snitzer 2013-12-05 15:47:24 -05:00
parent 399caddfb1
commit 8c0f0e8c9f
1 changed files with 20 additions and 6 deletions
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26
drivers/md/dm-thin.c
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@ -164,7 +164,7 @@ struct pool {
struct pool_features pf;
bool low_water_triggered:1; /* A dm event has been sent */
bool no_free_space:1; /* A -ENOSPC warning has been issued */
bool no_free_space:1; /* bios will be requeued if set */
struct dm_bio_prison *prison;
struct dm_kcopyd_client *copier;
@ -982,6 +982,20 @@ static void retry_on_resume(struct bio *bio)
spin_unlock_irqrestore(&pool->lock, flags);
}
static void handle_unserviceable_bio(struct pool *pool, struct bio *bio)
{
/*
* When pool is read-only, no cell locking is needed because
* nothing is changing.
*/
WARN_ON_ONCE(get_pool_mode(pool) != PM_READ_ONLY);
if (pool->no_free_space)
retry_on_resume(bio);
else
bio_io_error(bio);
}
static void retry_bios_on_resume(struct pool *pool, struct dm_bio_prison_cell *cell)
{
struct bio *bio;
@ -991,7 +1005,7 @@ static void retry_bios_on_resume(struct pool *pool, struct dm_bio_prison_cell *c
cell_release(pool, cell, &bios);
while ((bio = bio_list_pop(&bios)))
retry_on_resume(bio);
handle_unserviceable_bio(pool, bio);
}
static void process_discard(struct thin_c *tc, struct bio *bio)
@ -1245,7 +1259,7 @@ static void process_bio_read_only(struct thin_c *tc, struct bio *bio)
switch (r) {
case 0:
if (lookup_result.shared && (rw == WRITE) && bio->bi_size)
bio_io_error(bio);
handle_unserviceable_bio(tc->pool, bio);
else {
inc_all_io_entry(tc->pool, bio);
remap_and_issue(tc, bio, lookup_result.block);
@ -1254,7 +1268,7 @@ static void process_bio_read_only(struct thin_c *tc, struct bio *bio)
case -ENODATA:
if (rw != READ) {
bio_io_error(bio);
handle_unserviceable_bio(tc->pool, bio);
break;
}
@ -1565,9 +1579,9 @@ static int thin_bio_map(struct dm_target *ti, struct bio *bio)
if (get_pool_mode(tc->pool) == PM_READ_ONLY) {
/*
* This block isn't provisioned, and we have no way
* of doing so. Just error it.
* of doing so.
*/
bio_io_error(bio);
handle_unserviceable_bio(tc->pool, bio);
return DM_MAPIO_SUBMITTED;
}
/* fall through */