From 7c3c7cb99c771c4ce6a01a95e969dbc576fd7533 Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Fri, 7 Dec 2018 13:23:32 +0000 Subject: [PATCH] Btrfs: scrub, move setup of nofs contexts higher in the stack 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 Reviewed-by: David Sterba Signed-off-by: David Sterba --- 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 367ab0911c01..099eb3c8f86b 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; @@ -841,6 +833,7 @@ 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); @@ -865,6 +858,16 @@ static int scrub_handle_errored_block(struct scrub_block *sblock_to_check) have_csum = sblock_to_check->pagev[0]->have_csum; 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 @@ -874,6 +877,7 @@ 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++; @@ -913,7 +917,7 @@ 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++; @@ -1211,6 +1215,7 @@ out: } ret = unlock_full_stripe(fs_info, logical, full_stripe_locked); + memalloc_nofs_restore(nofs_flag); if (ret < 0) return ret; return 0; @@ -1629,19 +1634,8 @@ 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; -- 2.30.2