On Fri, Oct 23, 2015 at 4:11 PM, Jeff Mahoney <jeffm@xxxxxxxx> wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> On 10/23/15 4:03 AM, Zhao Lei wrote:
>> Since we set source bg to readonly in scrub/replace, we don't need
>> to consider confliction of no-cow write in scrub/replace operaion.
>
> What happens if there's a read failure? IIRC the initial purpose of
> this code was to correct read failures during scrub and device
> replacement by fetching the bad extent from another device if one is
> available.
And we don't have xfstests, or any other automated test suite, to test
those code paths.
So completely useless to run xfstests in a loop for 5 days, especially
the generic tests which never trigger scrub runs...
>
> See commit 0ef8e45158f (btrfs scrub: add fixup code for errors on
> nodatasum files)
>
> - -Jeff
>
>> This patch removes special code for no-cow mode in scrub/replace,
>> reduced 670 lines.
>>
>> Tested by continuous xfstests in 5 days, include generic and btrfs
>> groups with 10 mount options include nodatacow.
>>
>> Signed-off-by: Zhao Lei <zhaolei@xxxxxxxxxxxxxx> ---
>> fs/btrfs/ctree.h | 1 - fs/btrfs/scrub.c | 669
>> ------------------------------------------------------- 2 files
>> changed, 670 deletions(-)
>>
>> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index
>> 938efe3..3387509 100644 --- a/fs/btrfs/ctree.h +++
>> b/fs/btrfs/ctree.h @@ -1688,7 +1688,6 @@ struct btrfs_fs_info { int
>> scrub_workers_refcnt; struct btrfs_workqueue *scrub_workers; struct
>> btrfs_workqueue *scrub_wr_completion_workers; - struct
>> btrfs_workqueue *scrub_nocow_workers; struct btrfs_workqueue
>> *scrub_parity_workers;
>>
>> #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY diff --git
>> a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index d64f557..6027679
>> 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -205,32
>> +205,6 @@ struct scrub_ctx { atomic_t refs; };
>>
>> -struct scrub_fixup_nodatasum { - struct scrub_ctx *sctx; - struct
>> btrfs_device *dev; - u64 logical; - struct btrfs_root *root; -
>> struct btrfs_work work; - int mirror_num; -}; - -struct
>> scrub_nocow_inode { - u64 inum; - u64 offset; - u64 root; -
>> struct list_head list; -}; - -struct scrub_copy_nocow_ctx { -
>> struct scrub_ctx *sctx; - u64 logical; - u64 len; - int
>> mirror_num; - u64 physical_for_dev_replace; - struct list_head
>> inodes; - struct btrfs_work work; -}; - struct scrub_warning {
>> struct btrfs_path *path; u64 extent_item_size; @@ -242,8 +216,6
>> @@ struct scrub_warning {
>>
>> static void scrub_pending_bio_inc(struct scrub_ctx *sctx); static
>> void scrub_pending_bio_dec(struct scrub_ctx *sctx); -static void
>> scrub_pending_trans_workers_inc(struct scrub_ctx *sctx); -static
>> void scrub_pending_trans_workers_dec(struct scrub_ctx *sctx);
>> static int scrub_handle_errored_block(struct scrub_block
>> *sblock_to_check); static int scrub_setup_recheck_block(struct
>> scrub_block *original_sblock, struct scrub_block
>> *sblocks_for_recheck); @@ -298,13 +270,6 @@ static int
>> scrub_add_page_to_wr_bio(struct scrub_ctx *sctx, static void
>> scrub_wr_submit(struct scrub_ctx *sctx); static void
>> scrub_wr_bio_end_io(struct bio *bio, int err); static void
>> scrub_wr_bio_end_io_worker(struct btrfs_work *work); -static int
>> write_page_nocow(struct scrub_ctx *sctx, - u64
>> physical_for_dev_replace, struct page *page); -static int
>> copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root, -
>> struct scrub_copy_nocow_ctx *ctx); -static int
>> copy_nocow_pages(struct scrub_ctx *sctx, u64 logical, u64 len, -
>> int mirror_num, u64 physical_for_dev_replace); -static void
>> copy_nocow_pages_worker(struct btrfs_work *work); static void
>> __scrub_blocked_if_needed(struct btrfs_fs_info *fs_info); static
>> void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info); static
>> void scrub_put_ctx(struct scrub_ctx *sctx); @@ -355,60 +320,6 @@
>> static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info)
>> scrub_pause_off(fs_info); }
>>
>> -/* - * used for workers that require transaction commits (i.e.,
>> for the - * NOCOW case) - */ -static void
>> scrub_pending_trans_workers_inc(struct scrub_ctx *sctx) -{ - struct
>> btrfs_fs_info *fs_info = sctx->dev_root->fs_info; - -
>> atomic_inc(&sctx->refs); - /* - * increment scrubs_running to
>> prevent cancel requests from - * completing as long as a worker is
>> running. we must also - * increment scrubs_paused to prevent
>> deadlocking on pause - * requests used for transactions commits
>> (as the worker uses a - * transaction context). it is safe to
>> regard the worker - * as paused for all matters practical.
>> effectively, we only - * avoid cancellation requests from
>> completing. - */ - mutex_lock(&fs_info->scrub_lock); -
>> atomic_inc(&fs_info->scrubs_running); -
>> atomic_inc(&fs_info->scrubs_paused); -
>> mutex_unlock(&fs_info->scrub_lock); - - /* - * check if
>> @scrubs_running=@scrubs_paused condition - * inside wait_event()
>> is not an atomic operation. - * which means we may inc/dec
>> @scrub_running/paused - * at any time. Let's wake up
>> @scrub_pause_wait as - * much as we can to let commit transaction
>> blocked less. - */ - wake_up(&fs_info->scrub_pause_wait); - -
>> atomic_inc(&sctx->workers_pending); -} - -/* used for workers that
>> require transaction commits */ -static void
>> scrub_pending_trans_workers_dec(struct scrub_ctx *sctx) -{ - struct
>> btrfs_fs_info *fs_info = sctx->dev_root->fs_info; - - /* - * see
>> scrub_pending_trans_workers_inc() why we're pretending - * to be
>> paused in the scrub counters - */ -
>> mutex_lock(&fs_info->scrub_lock); -
>> atomic_dec(&fs_info->scrubs_running); -
>> atomic_dec(&fs_info->scrubs_paused); -
>> mutex_unlock(&fs_info->scrub_lock); -
>> atomic_dec(&sctx->workers_pending); -
>> wake_up(&fs_info->scrub_pause_wait); - wake_up(&sctx->list_wait); -
>> scrub_put_ctx(sctx); -} - static void scrub_free_csums(struct
>> scrub_ctx *sctx) { while (!list_empty(&sctx->csum_list)) { @@
>> -686,194 +597,6 @@ out: btrfs_free_path(path); }
>>
>> -static int scrub_fixup_readpage(u64 inum, u64 offset, u64 root,
>> void *fixup_ctx) -{ - struct page *page = NULL; - unsigned long
>> index; - struct scrub_fixup_nodatasum *fixup = fixup_ctx; - int
>> ret; - int corrected = 0; - struct btrfs_key key; - struct inode
>> *inode = NULL; - struct btrfs_fs_info *fs_info; - u64 end = offset
>> + PAGE_SIZE - 1; - struct btrfs_root *local_root; - int
>> srcu_index; - - key.objectid = root; - key.type =
>> BTRFS_ROOT_ITEM_KEY; - key.offset = (u64)-1; - - fs_info =
>> fixup->root->fs_info; - srcu_index =
>> srcu_read_lock(&fs_info->subvol_srcu); - - local_root =
>> btrfs_read_fs_root_no_name(fs_info, &key); - if
>> (IS_ERR(local_root)) { - srcu_read_unlock(&fs_info->subvol_srcu,
>> srcu_index); - return PTR_ERR(local_root); - } - - key.type =
>> BTRFS_INODE_ITEM_KEY; - key.objectid = inum; - key.offset = 0; -
>> inode = btrfs_iget(fs_info->sb, &key, local_root, NULL); -
>> srcu_read_unlock(&fs_info->subvol_srcu, srcu_index); - if
>> (IS_ERR(inode)) - return PTR_ERR(inode); - - index = offset >>
>> PAGE_CACHE_SHIFT; - - page = find_or_create_page(inode->i_mapping,
>> index, GFP_NOFS); - if (!page) { - ret = -ENOMEM; - goto out; -
>> } - - if (PageUptodate(page)) { - if (PageDirty(page)) { - /* -
>> * we need to write the data to the defect sector. the - * data
>> that was in that sector is not in memory, - * because the page
>> was modified. we must not write the - * modified page to that
>> sector. - * - * TODO: what could be done here: wait for the
>> delalloc - * runner to write out that page (might involve
>> - * COW) and see whether the sector is still - *
>> referenced afterwards. - * - * For the meantime, we'll treat
>> this error - * incorrectable, although there is a chance that a
>> - * later scrub will find the bad sector again and that - *
>> there's no dirty page in memory, then. - */ - ret = -EIO; -
>> goto out; - } - ret = repair_io_failure(inode, offset,
>> PAGE_SIZE, - fixup->logical, page, - offset -
>> page_offset(page), - fixup->mirror_num); - unlock_page(page);
>> - corrected = !ret; - } else { - /* - * we need to get good
>> data first. the general readpage path - * will call
>> repair_io_failure for us, we just have to make - * sure we read
>> the bad mirror. - */ - ret =
>> set_extent_bits(&BTRFS_I(inode)->io_tree, offset, end, -
>> EXTENT_DAMAGED, GFP_NOFS); - if (ret) { - /* set_extent_bits
>> should give proper error */ - WARN_ON(ret > 0); - if (ret > 0)
>> - ret = -EFAULT; - goto out; - } - - ret =
>> extent_read_full_page(&BTRFS_I(inode)->io_tree, page, -
>> btrfs_get_extent, - fixup->mirror_num); -
>> wait_on_page_locked(page); - - corrected =
>> !test_range_bit(&BTRFS_I(inode)->io_tree, offset, - end,
>> EXTENT_DAMAGED, 0, NULL); - if (!corrected) -
>> clear_extent_bits(&BTRFS_I(inode)->io_tree, offset, end, -
>> EXTENT_DAMAGED, GFP_NOFS); - } - -out: - if (page) -
>> put_page(page); - - iput(inode); - - if (ret < 0) - return ret; -
>> - if (ret == 0 && corrected) { - /* - * we only need to call
>> readpage for one of the inodes belonging - * to this extent. so
>> make iterate_extent_inodes stop - */ - return 1; - } - - return
>> -EIO; -} - -static void scrub_fixup_nodatasum(struct btrfs_work
>> *work) -{ - int ret; - struct scrub_fixup_nodatasum *fixup; -
>> struct scrub_ctx *sctx; - struct btrfs_trans_handle *trans = NULL;
>> - struct btrfs_path *path; - int uncorrectable = 0; - - fixup =
>> container_of(work, struct scrub_fixup_nodatasum, work); - sctx =
>> fixup->sctx; - - path = btrfs_alloc_path(); - if (!path) { -
>> spin_lock(&sctx->stat_lock); - ++sctx->stat.malloc_errors; -
>> spin_unlock(&sctx->stat_lock); - uncorrectable = 1; - goto out; -
>> } - - trans = btrfs_join_transaction(fixup->root); - if
>> (IS_ERR(trans)) { - uncorrectable = 1; - goto out; - } - - /* -
>> * the idea is to trigger a regular read through the standard path.
>> we - * read a page from the (failed) logical address by specifying
>> the - * corresponding copynum of the failed sector. thus, that
>> readpage is - * expected to fail. - * that is the point where
>> on-the-fly error correction will kick in - * (once it's finished)
>> and rewrite the failed sector if a good copy - * can be found. -
>> */ - ret = iterate_inodes_from_logical(fixup->logical,
>> fixup->root->fs_info, - path, scrub_fixup_readpage, -
>> fixup); - if (ret < 0) { - uncorrectable = 1; - goto out; - } -
>> WARN_ON(ret != 1); - - spin_lock(&sctx->stat_lock); -
>> ++sctx->stat.corrected_errors; - spin_unlock(&sctx->stat_lock); -
>> -out: - if (trans && !IS_ERR(trans)) -
>> btrfs_end_transaction(trans, fixup->root); - if (uncorrectable) { -
>> spin_lock(&sctx->stat_lock); - ++sctx->stat.uncorrectable_errors;
>> - spin_unlock(&sctx->stat_lock); - btrfs_dev_replace_stats_inc( -
>> &sctx->dev_root->fs_info->dev_replace. -
>> num_uncorrectable_read_errors); -
>> printk_ratelimited_in_rcu(KERN_ERR "BTRFS: " - "unable to
>> fixup (nodatasum) error at logical %llu on dev %s\n", -
>> fixup->logical, rcu_str_deref(fixup->dev->name)); - } - -
>> btrfs_free_path(path); - kfree(fixup); - -
>> scrub_pending_trans_workers_dec(sctx); -} - static inline void
>> scrub_get_recover(struct scrub_recover *recover) {
>> atomic_inc(&recover->refs); @@ -940,11 +663,6 @@ static int
>> scrub_handle_errored_block(struct scrub_block *sblock_to_check)
>> csum = sblock_to_check->pagev[0]->csum; dev =
>> sblock_to_check->pagev[0]->dev;
>>
>> - if (sctx->is_dev_replace && !is_metadata && !have_csum) { -
>> sblocks_for_recheck = NULL; - goto nodatasum_case; - } - /* * read
>> all mirrors one after the other. This includes to * re-read the
>> extent or metadata block that failed (that was @@ -1058,36 +776,6
>> @@ static int scrub_handle_errored_block(struct scrub_block
>> *sblock_to_check) goto out; }
>>
>> - if (!is_metadata && !have_csum) { - struct scrub_fixup_nodatasum
>> *fixup_nodatasum; - - WARN_ON(sctx->is_dev_replace); -
>> -nodatasum_case: - - /* - * !is_metadata and !have_csum, this
>> means that the data - * might not be COW'ed, that it might be
>> modified - * concurrently. The general strategy to work on the -
>> * commit root does not help in the case when COW is not - *
>> used. - */ - fixup_nodatasum = kzalloc(sizeof(*fixup_nodatasum),
>> GFP_NOFS); - if (!fixup_nodatasum) - goto
>> did_not_correct_error; - fixup_nodatasum->sctx = sctx; -
>> fixup_nodatasum->dev = dev; - fixup_nodatasum->logical = logical;
>> - fixup_nodatasum->root = fs_info->extent_root; -
>> fixup_nodatasum->mirror_num = failed_mirror_index + 1; -
>> scrub_pending_trans_workers_inc(sctx); -
>> btrfs_init_work(&fixup_nodatasum->work, btrfs_scrub_helper, -
>> scrub_fixup_nodatasum, NULL, NULL); -
>> btrfs_queue_work(fs_info->scrub_workers, -
>> &fixup_nodatasum->work); - goto out; - } - /* * now build and
>> submit the bios for the other mirrors, check * checksums. @@
>> -2575,23 +2263,9 @@ static int scrub_extent(struct scrub_ctx *sctx,
>> u64 logical, u64 len, while (len) { u64 l = min_t(u64, len,
>> blocksize); int have_csum = 0; - - if (flags &
>> BTRFS_EXTENT_FLAG_DATA) { - /* push csums to sbio */ -
>> have_csum = scrub_find_csum(sctx, logical, l, csum); - if
>> (have_csum == 0) - ++sctx->stat.no_csum; - if
>> (sctx->is_dev_replace && !have_csum) { - ret =
>> copy_nocow_pages(sctx, logical, l, - mirror_num, -
>> physical_for_dev_replace); - goto behind_scrub_pages; - } -
>> } ret = scrub_pages(sctx, logical, l, physical, dev, flags, gen,
>> mirror_num, have_csum ? csum : NULL, 0, physical_for_dev_replace);
>> -behind_scrub_pages: if (ret) return ret; len -= l; @@ -3762,10
>> +3436,6 @@ static noinline_for_stack int scrub_workers_get(struct
>> btrfs_fs_info *fs_info, if (!fs_info->scrub_wr_completion_workers)
>> goto fail_scrub_wr_completion_workers;
>>
>> - fs_info->scrub_nocow_workers = -
>> btrfs_alloc_workqueue("btrfs-scrubnc", flags, 1, 0); - if
>> (!fs_info->scrub_nocow_workers) - goto fail_scrub_nocow_workers;
>> fs_info->scrub_parity_workers =
>> btrfs_alloc_workqueue("btrfs-scrubparity", flags, max_active, 2);
>> @@ -3776,8 +3446,6 @@ static noinline_for_stack int
>> scrub_workers_get(struct btrfs_fs_info *fs_info, return 0;
>>
>> fail_scrub_parity_workers: -
>> btrfs_destroy_workqueue(fs_info->scrub_nocow_workers);
>> -fail_scrub_nocow_workers:
>> btrfs_destroy_workqueue(fs_info->scrub_wr_completion_workers);
>> fail_scrub_wr_completion_workers:
>> btrfs_destroy_workqueue(fs_info->scrub_workers); @@ -3790,7 +3458,6
>> @@ static noinline_for_stack void scrub_workers_put(struct
>> btrfs_fs_info *fs_info) if (--fs_info->scrub_workers_refcnt == 0)
>> { btrfs_destroy_workqueue(fs_info->scrub_workers);
>> btrfs_destroy_workqueue(fs_info->scrub_wr_completion_workers); -
>> btrfs_destroy_workqueue(fs_info->scrub_nocow_workers);
>> btrfs_destroy_workqueue(fs_info->scrub_parity_workers); }
>> WARN_ON(fs_info->scrub_workers_refcnt < 0); @@ -4081,339 +3748,3 @@
>> static void scrub_free_wr_ctx(struct scrub_wr_ctx *wr_ctx)
>> mutex_unlock(&wr_ctx->wr_lock); }
>>
>> -static int copy_nocow_pages(struct scrub_ctx *sctx, u64 logical,
>> u64 len, - int mirror_num, u64 physical_for_dev_replace) -{ -
>> struct scrub_copy_nocow_ctx *nocow_ctx; - struct btrfs_fs_info
>> *fs_info = sctx->dev_root->fs_info; - - nocow_ctx =
>> kzalloc(sizeof(*nocow_ctx), GFP_NOFS); - if (!nocow_ctx) { -
>> spin_lock(&sctx->stat_lock); - sctx->stat.malloc_errors++; -
>> spin_unlock(&sctx->stat_lock); - return -ENOMEM; - } - -
>> scrub_pending_trans_workers_inc(sctx); - - nocow_ctx->sctx = sctx;
>> - nocow_ctx->logical = logical; - nocow_ctx->len = len; -
>> nocow_ctx->mirror_num = mirror_num; -
>> nocow_ctx->physical_for_dev_replace = physical_for_dev_replace; -
>> btrfs_init_work(&nocow_ctx->work, btrfs_scrubnc_helper, -
>> copy_nocow_pages_worker, NULL, NULL); -
>> INIT_LIST_HEAD(&nocow_ctx->inodes); -
>> btrfs_queue_work(fs_info->scrub_nocow_workers, -
>> &nocow_ctx->work); - - return 0; -} - -static int
>> record_inode_for_nocow(u64 inum, u64 offset, u64 root, void *ctx)
>> -{ - struct scrub_copy_nocow_ctx *nocow_ctx = ctx; - struct
>> scrub_nocow_inode *nocow_inode; - - nocow_inode =
>> kzalloc(sizeof(*nocow_inode), GFP_NOFS); - if (!nocow_inode) -
>> return -ENOMEM; - nocow_inode->inum = inum; - nocow_inode->offset =
>> offset; - nocow_inode->root = root; -
>> list_add_tail(&nocow_inode->list, &nocow_ctx->inodes); - return 0;
>> -} - -#define COPY_COMPLETE 1 - -static void
>> copy_nocow_pages_worker(struct btrfs_work *work) -{ - struct
>> scrub_copy_nocow_ctx *nocow_ctx = - container_of(work, struct
>> scrub_copy_nocow_ctx, work); - struct scrub_ctx *sctx =
>> nocow_ctx->sctx; - u64 logical = nocow_ctx->logical; - u64 len =
>> nocow_ctx->len; - int mirror_num = nocow_ctx->mirror_num; - u64
>> physical_for_dev_replace = nocow_ctx->physical_for_dev_replace; -
>> int ret; - struct btrfs_trans_handle *trans = NULL; - struct
>> btrfs_fs_info *fs_info; - struct btrfs_path *path; - struct
>> btrfs_root *root; - int not_written = 0; - - fs_info =
>> sctx->dev_root->fs_info; - root = fs_info->extent_root; - - path =
>> btrfs_alloc_path(); - if (!path) { - spin_lock(&sctx->stat_lock);
>> - sctx->stat.malloc_errors++; - spin_unlock(&sctx->stat_lock); -
>> not_written = 1; - goto out; - } - - trans =
>> btrfs_join_transaction(root); - if (IS_ERR(trans)) { - not_written
>> = 1; - goto out; - } - - ret =
>> iterate_inodes_from_logical(logical, fs_info, path, -
>> record_inode_for_nocow, nocow_ctx); - if (ret != 0 && ret !=
>> -ENOENT) { - btrfs_warn(fs_info, "iterate_inodes_from_logical()
>> failed: log %llu, " - "phys %llu, len %llu, mir %u, ret %d", -
>> logical, physical_for_dev_replace, len, mirror_num, - ret); -
>> not_written = 1; - goto out; - } - - btrfs_end_transaction(trans,
>> root); - trans = NULL; - while (!list_empty(&nocow_ctx->inodes)) {
>> - struct scrub_nocow_inode *entry; - entry =
>> list_first_entry(&nocow_ctx->inodes, - struct
>> scrub_nocow_inode, - list); - list_del_init(&entry->list); -
>> ret = copy_nocow_pages_for_inode(entry->inum, entry->offset, -
>> entry->root, nocow_ctx); - kfree(entry); - if (ret ==
>> COPY_COMPLETE) { - ret = 0; - break; - } else if (ret) { -
>> break; - } - } -out: - while (!list_empty(&nocow_ctx->inodes)) { -
>> struct scrub_nocow_inode *entry; - entry =
>> list_first_entry(&nocow_ctx->inodes, - struct
>> scrub_nocow_inode, - list); - list_del_init(&entry->list); -
>> kfree(entry); - } - if (trans && !IS_ERR(trans)) -
>> btrfs_end_transaction(trans, root); - if (not_written) -
>> btrfs_dev_replace_stats_inc(&fs_info->dev_replace. -
>> num_uncorrectable_read_errors); - - btrfs_free_path(path); -
>> kfree(nocow_ctx); - - scrub_pending_trans_workers_dec(sctx); -} -
>> -static int check_extent_to_block(struct inode *inode, u64 start,
>> u64 len, - u64 logical) -{ - struct extent_state *cached_state
>> = NULL; - struct btrfs_ordered_extent *ordered; - struct
>> extent_io_tree *io_tree; - struct extent_map *em; - u64 lockstart =
>> start, lockend = start + len - 1; - int ret = 0; - - io_tree =
>> &BTRFS_I(inode)->io_tree; - - lock_extent_bits(io_tree, lockstart,
>> lockend, 0, &cached_state); - ordered =
>> btrfs_lookup_ordered_range(inode, lockstart, len); - if (ordered)
>> { - btrfs_put_ordered_extent(ordered); - ret = 1; - goto
>> out_unlock; - } - - em = btrfs_get_extent(inode, NULL, 0, start,
>> len, 0); - if (IS_ERR(em)) { - ret = PTR_ERR(em); - goto
>> out_unlock; - } - - /* - * This extent does not actually cover the
>> logical extent anymore, - * move on to the next inode. - */ - if
>> (em->block_start > logical || - em->block_start + em->block_len
>> < logical + len) { - free_extent_map(em); - ret = 1; - goto
>> out_unlock; - } - free_extent_map(em); - -out_unlock: -
>> unlock_extent_cached(io_tree, lockstart, lockend, &cached_state, -
>> GFP_NOFS); - return ret; -} - -static int
>> copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root, -
>> struct scrub_copy_nocow_ctx *nocow_ctx) -{ - struct btrfs_fs_info
>> *fs_info = nocow_ctx->sctx->dev_root->fs_info; - struct btrfs_key
>> key; - struct inode *inode; - struct page *page; - struct
>> btrfs_root *local_root; - struct extent_io_tree *io_tree; - u64
>> physical_for_dev_replace; - u64 nocow_ctx_logical; - u64 len =
>> nocow_ctx->len; - unsigned long index; - int srcu_index; - int ret
>> = 0; - int err = 0; - - key.objectid = root; - key.type =
>> BTRFS_ROOT_ITEM_KEY; - key.offset = (u64)-1; - - srcu_index =
>> srcu_read_lock(&fs_info->subvol_srcu); - - local_root =
>> btrfs_read_fs_root_no_name(fs_info, &key); - if
>> (IS_ERR(local_root)) { - srcu_read_unlock(&fs_info->subvol_srcu,
>> srcu_index); - return PTR_ERR(local_root); - } - - key.type =
>> BTRFS_INODE_ITEM_KEY; - key.objectid = inum; - key.offset = 0; -
>> inode = btrfs_iget(fs_info->sb, &key, local_root, NULL); -
>> srcu_read_unlock(&fs_info->subvol_srcu, srcu_index); - if
>> (IS_ERR(inode)) - return PTR_ERR(inode); - - /* Avoid
>> truncate/dio/punch hole.. */ - mutex_lock(&inode->i_mutex); -
>> inode_dio_wait(inode); - - physical_for_dev_replace =
>> nocow_ctx->physical_for_dev_replace; - io_tree =
>> &BTRFS_I(inode)->io_tree; - nocow_ctx_logical =
>> nocow_ctx->logical; - - ret = check_extent_to_block(inode, offset,
>> len, nocow_ctx_logical); - if (ret) { - ret = ret > 0 ? 0 : ret; -
>> goto out; - } - - while (len >= PAGE_CACHE_SIZE) { - index =
>> offset >> PAGE_CACHE_SHIFT; -again: - page =
>> find_or_create_page(inode->i_mapping, index, GFP_NOFS); - if
>> (!page) { - btrfs_err(fs_info, "find_or_create_page() failed"); -
>> ret = -ENOMEM; - goto out; - } - - if (PageUptodate(page)) { -
>> if (PageDirty(page)) - goto next_page; - } else { -
>> ClearPageError(page); - err = extent_read_full_page(io_tree,
>> page, - btrfs_get_extent, -
>> nocow_ctx->mirror_num); - if (err) { - ret = err; - goto
>> next_page; - } - - lock_page(page); - /* - * If the page
>> has been remove from the page cache, - * the data on it is
>> meaningless, because it may be - * old one, the new data may be
>> written into the new - * page in the page cache. - */ - if
>> (page->mapping != inode->i_mapping) { - unlock_page(page); -
>> page_cache_release(page); - goto again; - } - if
>> (!PageUptodate(page)) { - ret = -EIO; - goto next_page; -
>> } - } - - ret = check_extent_to_block(inode, offset, len, -
>> nocow_ctx_logical); - if (ret) { - ret = ret > 0 ? 0 : ret; -
>> goto next_page; - } - - err = write_page_nocow(nocow_ctx->sctx, -
>> physical_for_dev_replace, page); - if (err) - ret = err;
>> -next_page: - unlock_page(page); - page_cache_release(page); - -
>> if (ret) - break; - - offset += PAGE_CACHE_SIZE; -
>> physical_for_dev_replace += PAGE_CACHE_SIZE; - nocow_ctx_logical
>> += PAGE_CACHE_SIZE; - len -= PAGE_CACHE_SIZE; - } - ret =
>> COPY_COMPLETE; -out: - mutex_unlock(&inode->i_mutex); -
>> iput(inode); - return ret; -} - -static int write_page_nocow(struct
>> scrub_ctx *sctx, - u64 physical_for_dev_replace, struct page
>> *page) -{ - struct bio *bio; - struct btrfs_device *dev; - int
>> ret; - - dev = sctx->wr_ctx.tgtdev; - if (!dev) - return -EIO; -
>> if (!dev->bdev) { - printk_ratelimited(KERN_WARNING - "BTRFS:
>> scrub write_page_nocow(bdev == NULL) is unexpected!\n"); - return
>> -EIO; - } - bio = btrfs_io_bio_alloc(GFP_NOFS, 1); - if (!bio) { -
>> spin_lock(&sctx->stat_lock); - sctx->stat.malloc_errors++; -
>> spin_unlock(&sctx->stat_lock); - return -ENOMEM; - } -
>> bio->bi_iter.bi_size = 0; - bio->bi_iter.bi_sector =
>> physical_for_dev_replace >> 9; - bio->bi_bdev = dev->bdev; - ret =
>> bio_add_page(bio, page, PAGE_CACHE_SIZE, 0); - if (ret !=
>> PAGE_CACHE_SIZE) { -leave_with_eio: - bio_put(bio); -
>> btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_WRITE_ERRS); -
>> return -EIO; - } - - if (btrfsic_submit_bio_wait(WRITE_SYNC, bio))
>> - goto leave_with_eio; - - bio_put(bio); - return 0; -}
>>
>
>
> - --
> Jeff Mahoney
> SUSE Labs
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--
Filipe David Manana,
"Reasonable men adapt themselves to the world.
Unreasonable men adapt the world to themselves.
That's why all progress depends on unreasonable men."
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