From: Josef Bacik Date: Wed, 7 Aug 2013 18:54:37 +0000 (-0400) Subject: Btrfs: deal with enomem in the rewind path X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=db7f3436c1c186f8271018751fcb338cf3706e8d;p=linux-beck.git Btrfs: deal with enomem in the rewind path We can get ENOMEM trying to allocate dummy bufs for the rewind operation of the tree mod log. Instead of BUG_ON()'ing in this case pass up ENOMEM. I looked back through the callers and I'm pretty sure I got everybody who did BUG_ON(ret) in this path. Thanks, Signed-off-by: Josef Bacik Signed-off-by: Chris Mason --- diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 0d5c686f2b98..1dd8a71f567d 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -1211,7 +1211,11 @@ tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb, BUG_ON(tm->slot != 0); eb_rewin = alloc_dummy_extent_buffer(eb->start, fs_info->tree_root->nodesize); - BUG_ON(!eb_rewin); + if (!eb_rewin) { + btrfs_tree_read_unlock(eb); + free_extent_buffer(eb); + return NULL; + } btrfs_set_header_bytenr(eb_rewin, eb->start); btrfs_set_header_backref_rev(eb_rewin, btrfs_header_backref_rev(eb)); @@ -1219,7 +1223,11 @@ tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb, btrfs_set_header_level(eb_rewin, btrfs_header_level(eb)); } else { eb_rewin = btrfs_clone_extent_buffer(eb); - BUG_ON(!eb_rewin); + if (!eb_rewin) { + btrfs_tree_read_unlock(eb); + free_extent_buffer(eb); + return NULL; + } } btrfs_tree_read_unlock(eb); @@ -2772,6 +2780,10 @@ again: BTRFS_READ_LOCK); } b = tree_mod_log_rewind(root->fs_info, b, time_seq); + if (!b) { + ret = -ENOMEM; + goto done; + } p->locks[level] = BTRFS_READ_LOCK; p->nodes[level] = b; } else { diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index c137f98fbd24..ef25c7d048e2 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -4222,6 +4222,76 @@ static void __free_extent_buffer(struct extent_buffer *eb) kmem_cache_free(extent_buffer_cache, eb); } +static int extent_buffer_under_io(struct extent_buffer *eb) +{ + return (atomic_read(&eb->io_pages) || + test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags) || + test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)); +} + +/* + * Helper for releasing extent buffer page. + */ +static void btrfs_release_extent_buffer_page(struct extent_buffer *eb, + unsigned long start_idx) +{ + unsigned long index; + unsigned long num_pages; + struct page *page; + int mapped = !test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags); + + BUG_ON(extent_buffer_under_io(eb)); + + num_pages = num_extent_pages(eb->start, eb->len); + index = start_idx + num_pages; + if (start_idx >= index) + return; + + do { + index--; + page = extent_buffer_page(eb, index); + if (page && mapped) { + spin_lock(&page->mapping->private_lock); + /* + * We do this since we'll remove the pages after we've + * removed the eb from the radix tree, so we could race + * and have this page now attached to the new eb. So + * only clear page_private if it's still connected to + * this eb. + */ + if (PagePrivate(page) && + page->private == (unsigned long)eb) { + BUG_ON(test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)); + BUG_ON(PageDirty(page)); + BUG_ON(PageWriteback(page)); + /* + * We need to make sure we haven't be attached + * to a new eb. + */ + ClearPagePrivate(page); + set_page_private(page, 0); + /* One for the page private */ + page_cache_release(page); + } + spin_unlock(&page->mapping->private_lock); + + } + if (page) { + /* One for when we alloced the page */ + page_cache_release(page); + } + } while (index != start_idx); +} + +/* + * Helper for releasing the extent buffer. + */ +static inline void btrfs_release_extent_buffer(struct extent_buffer *eb) +{ + btrfs_release_extent_buffer_page(eb, 0); + __free_extent_buffer(eb); +} + static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree, u64 start, unsigned long len, @@ -4276,7 +4346,10 @@ struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src) for (i = 0; i < num_pages; i++) { p = alloc_page(GFP_ATOMIC); - BUG_ON(!p); + if (!p) { + btrfs_release_extent_buffer(new); + return NULL; + } attach_extent_buffer_page(new, p); WARN_ON(PageDirty(p)); SetPageUptodate(p); @@ -4317,76 +4390,6 @@ err: return NULL; } -static int extent_buffer_under_io(struct extent_buffer *eb) -{ - return (atomic_read(&eb->io_pages) || - test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags) || - test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)); -} - -/* - * Helper for releasing extent buffer page. - */ -static void btrfs_release_extent_buffer_page(struct extent_buffer *eb, - unsigned long start_idx) -{ - unsigned long index; - unsigned long num_pages; - struct page *page; - int mapped = !test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags); - - BUG_ON(extent_buffer_under_io(eb)); - - num_pages = num_extent_pages(eb->start, eb->len); - index = start_idx + num_pages; - if (start_idx >= index) - return; - - do { - index--; - page = extent_buffer_page(eb, index); - if (page && mapped) { - spin_lock(&page->mapping->private_lock); - /* - * We do this since we'll remove the pages after we've - * removed the eb from the radix tree, so we could race - * and have this page now attached to the new eb. So - * only clear page_private if it's still connected to - * this eb. - */ - if (PagePrivate(page) && - page->private == (unsigned long)eb) { - BUG_ON(test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)); - BUG_ON(PageDirty(page)); - BUG_ON(PageWriteback(page)); - /* - * We need to make sure we haven't be attached - * to a new eb. - */ - ClearPagePrivate(page); - set_page_private(page, 0); - /* One for the page private */ - page_cache_release(page); - } - spin_unlock(&page->mapping->private_lock); - - } - if (page) { - /* One for when we alloced the page */ - page_cache_release(page); - } - } while (index != start_idx); -} - -/* - * Helper for releasing the extent buffer. - */ -static inline void btrfs_release_extent_buffer(struct extent_buffer *eb) -{ - btrfs_release_extent_buffer_page(eb, 0); - __free_extent_buffer(eb); -} - static void check_buffer_tree_ref(struct extent_buffer *eb) { int refs;