From: Filipe Manana <fdman...@suse.com>
Since scrub workers only do memory allocation with GFP_KERNEL when they
need to perform repair, we can move the recent setup of the nofs context
up to scrub_handle_errored_block() instead of setting it up down the call
chain at insert_full_stripe_lock() and scrub_add_page_to_wr_bio(),
removing some duplicate code and comment. So the only paths for which a
scrub worker can do memory allocations using GFP_KERNEL are the following:
scrub_bio_end_io_worker()
scrub_block_complete()
scrub_handle_errored_block()
lock_full_stripe()
insert_full_stripe_lock()
-> kmalloc with GFP_KERNEL
scrub_bio_end_io_worker()
scrub_block_complete()
scrub_handle_errored_block()
scrub_write_page_to_dev_replace()
scrub_add_page_to_wr_bio()
-> kzalloc with GFP_KERNEL
Signed-off-by: Filipe Manana <fdman...@suse.com>
---
Applies on top of:
Btrfs: fix deadlock with memory reclaim during scrub
fs/btrfs/scrub.c | 34 ++++++++++++++--------------------
1 file changed, 14 insertions(+), 20 deletions(-)
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index bbd1b36f4918..f996f4064596 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -322,7 +322,6 @@ static struct full_stripe_lock *insert_full_stripe_lock(
struct rb_node *parent = NULL;
struct full_stripe_lock *entry;
struct full_stripe_lock *ret;
- unsigned int nofs_flag;
lockdep_assert_held(&locks_root->lock);
@@ -342,15 +341,8 @@ static struct full_stripe_lock *insert_full_stripe_lock(
/*
* Insert new lock.
- *
- * We must use GFP_NOFS because the scrub task might be waiting for a
- * worker task executing this function and in turn a transaction commit
- * might be waiting the scrub task to pause (which needs to wait for all
- * the worker tasks to complete before pausing).
*/
- nofs_flag = memalloc_nofs_save();
ret = kmalloc(sizeof(*ret), GFP_KERNEL);
- memalloc_nofs_restore(nofs_flag);
if (!ret)
return ERR_PTR(-ENOMEM);
ret->logical = fstripe_logical;
@@ -842,6 +834,7 @@ static int scrub_handle_errored_block(struct scrub_block
*sblock_to_check)
int page_num;
int success;
bool full_stripe_locked;
+ unsigned int nofs_flag;
static DEFINE_RATELIMIT_STATE(_rs, DEFAULT_RATELIMIT_INTERVAL,
DEFAULT_RATELIMIT_BURST);
@@ -867,6 +860,16 @@ static int scrub_handle_errored_block(struct scrub_block
*sblock_to_check)
dev = sblock_to_check->pagev[0]->dev;
/*
+ * We must use GFP_NOFS because the scrub task might be waiting for a
+ * worker task executing this function and in turn a transaction commit
+ * might be waiting the scrub task to pause (which needs to wait for all
+ * the worker tasks to complete before pausing).
+ * We do allocations in the workers through insert_full_stripe_lock()
+ * and scrub_add_page_to_wr_bio(), which happens down the call chain of
+ * this function.
+ */
+ nofs_flag = memalloc_nofs_save();
+ /*
* For RAID5/6, race can happen for a different device scrub thread.
* For data corruption, Parity and Data threads will both try
* to recovery the data.
@@ -875,6 +878,7 @@ static int scrub_handle_errored_block(struct scrub_block
*sblock_to_check)
*/
ret = lock_full_stripe(fs_info, logical, &full_stripe_locked);
if (ret < 0) {
+ memalloc_nofs_restore(nofs_flag);
spin_lock(&sctx->stat_lock);
if (ret == -ENOMEM)
sctx->stat.malloc_errors++;
@@ -914,7 +918,7 @@ static int scrub_handle_errored_block(struct scrub_block
*sblock_to_check)
*/
sblocks_for_recheck = kcalloc(BTRFS_MAX_MIRRORS,
- sizeof(*sblocks_for_recheck), GFP_NOFS);
+ sizeof(*sblocks_for_recheck), GFP_KERNEL);
if (!sblocks_for_recheck) {
spin_lock(&sctx->stat_lock);
sctx->stat.malloc_errors++;
@@ -1212,6 +1216,7 @@ static int scrub_handle_errored_block(struct scrub_block
*sblock_to_check)
}
ret = unlock_full_stripe(fs_info, logical, full_stripe_locked);
+ memalloc_nofs_restore(nofs_flag);
if (ret < 0)
return ret;
return 0;
@@ -1630,19 +1635,8 @@ static int scrub_add_page_to_wr_bio(struct scrub_ctx
*sctx,
mutex_lock(&sctx->wr_lock);
again:
if (!sctx->wr_curr_bio) {
- unsigned int nofs_flag;
-
- /*
- * We must use GFP_NOFS because the scrub task might be waiting
- * for a worker task executing this function and in turn a
- * transaction commit might be waiting the scrub task to pause
- * (which needs to wait for all the worker tasks to complete
- * before pausing).
- */
- nofs_flag = memalloc_nofs_save();
sctx->wr_curr_bio = kzalloc(sizeof(*sctx->wr_curr_bio),
GFP_KERNEL);
- memalloc_nofs_restore(nofs_flag);
if (!sctx->wr_curr_bio) {
mutex_unlock(&sctx->wr_lock);
return -ENOMEM;
--
2.11.0
