diff options
Diffstat (limited to 'fs/btrfs/extent_io.c')
| -rw-r--r-- | fs/btrfs/extent_io.c | 70 |
1 files changed, 39 insertions, 31 deletions
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 2776112db..41173701f 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -2773,13 +2773,19 @@ static int fiemap_next_leaf_item(struct btrfs_inode *inode, struct btrfs_path *p goto out; } - /* See the comment at fiemap_search_slot() about why we clone. */ - copy_extent_buffer_full(clone, path->nodes[0]); /* * Important to preserve the start field, for the optimizations when * checking if extents are shared (see extent_fiemap()). + * + * We must set ->start before calling copy_extent_buffer_full(). If we + * are on sub-pagesize blocksize, we use ->start to determine the offset + * into the folio where our eb exists, and if we update ->start after + * the fact then any subsequent reads of the eb may read from a + * different offset in the folio than where we originally copied into. */ clone->start = path->nodes[0]->start; + /* See the comment at fiemap_search_slot() about why we clone. */ + copy_extent_buffer_full(clone, path->nodes[0]); slot = path->slots[0]; btrfs_release_path(path); @@ -3656,6 +3662,8 @@ static struct extent_buffer *grab_extent_buffer( struct folio *folio = page_folio(page); struct extent_buffer *exists; + lockdep_assert_held(&page->mapping->i_private_lock); + /* * For subpage case, we completely rely on radix tree to ensure we * don't try to insert two ebs for the same bytenr. So here we always @@ -3723,13 +3731,14 @@ static int check_eb_alignment(struct btrfs_fs_info *fs_info, u64 start) * The caller needs to free the existing folios and retry using the same order. */ static int attach_eb_folio_to_filemap(struct extent_buffer *eb, int i, + struct btrfs_subpage *prealloc, struct extent_buffer **found_eb_ret) { struct btrfs_fs_info *fs_info = eb->fs_info; struct address_space *mapping = fs_info->btree_inode->i_mapping; const unsigned long index = eb->start >> PAGE_SHIFT; - struct folio *existing_folio; + struct folio *existing_folio = NULL; int ret; ASSERT(found_eb_ret); @@ -3741,12 +3750,14 @@ retry: ret = filemap_add_folio(mapping, eb->folios[i], index + i, GFP_NOFS | __GFP_NOFAIL); if (!ret) - return 0; + goto finish; existing_folio = filemap_lock_folio(mapping, index + i); /* The page cache only exists for a very short time, just retry. */ - if (IS_ERR(existing_folio)) + if (IS_ERR(existing_folio)) { + existing_folio = NULL; goto retry; + } /* For now, we should only have single-page folios for btree inode. */ ASSERT(folio_nr_pages(existing_folio) == 1); @@ -3757,14 +3768,13 @@ retry: return -EAGAIN; } - if (fs_info->nodesize < PAGE_SIZE) { - /* - * We're going to reuse the existing page, can drop our page - * and subpage structure now. - */ +finish: + spin_lock(&mapping->i_private_lock); + if (existing_folio && fs_info->nodesize < PAGE_SIZE) { + /* We're going to reuse the existing page, can drop our folio now. */ __free_page(folio_page(eb->folios[i], 0)); eb->folios[i] = existing_folio; - } else { + } else if (existing_folio) { struct extent_buffer *existing_eb; existing_eb = grab_extent_buffer(fs_info, @@ -3772,6 +3782,7 @@ retry: if (existing_eb) { /* The extent buffer still exists, we can use it directly. */ *found_eb_ret = existing_eb; + spin_unlock(&mapping->i_private_lock); folio_unlock(existing_folio); folio_put(existing_folio); return 1; @@ -3780,6 +3791,22 @@ retry: __free_page(folio_page(eb->folios[i], 0)); eb->folios[i] = existing_folio; } + eb->folio_size = folio_size(eb->folios[i]); + eb->folio_shift = folio_shift(eb->folios[i]); + /* Should not fail, as we have preallocated the memory. */ + ret = attach_extent_buffer_folio(eb, eb->folios[i], prealloc); + ASSERT(!ret); + /* + * To inform we have an extra eb under allocation, so that + * detach_extent_buffer_page() won't release the folio private when the + * eb hasn't been inserted into radix tree yet. + * + * The ref will be decreased when the eb releases the page, in + * detach_extent_buffer_page(). Thus needs no special handling in the + * error path. + */ + btrfs_folio_inc_eb_refs(fs_info, eb->folios[i]); + spin_unlock(&mapping->i_private_lock); return 0; } @@ -3791,7 +3818,6 @@ struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info, int attached = 0; struct extent_buffer *eb; struct extent_buffer *existing_eb = NULL; - struct address_space *mapping = fs_info->btree_inode->i_mapping; struct btrfs_subpage *prealloc = NULL; u64 lockdep_owner = owner_root; bool page_contig = true; @@ -3857,7 +3883,7 @@ reallocate: for (int i = 0; i < num_folios; i++) { struct folio *folio; - ret = attach_eb_folio_to_filemap(eb, i, &existing_eb); + ret = attach_eb_folio_to_filemap(eb, i, prealloc, &existing_eb); if (ret > 0) { ASSERT(existing_eb); goto out; @@ -3894,24 +3920,6 @@ reallocate: * and free the allocated page. */ folio = eb->folios[i]; - eb->folio_size = folio_size(folio); - eb->folio_shift = folio_shift(folio); - spin_lock(&mapping->i_private_lock); - /* Should not fail, as we have preallocated the memory */ - ret = attach_extent_buffer_folio(eb, folio, prealloc); - ASSERT(!ret); - /* - * To inform we have extra eb under allocation, so that - * detach_extent_buffer_page() won't release the folio private - * when the eb hasn't yet been inserted into radix tree. - * - * The ref will be decreased when the eb released the page, in - * detach_extent_buffer_page(). - * Thus needs no special handling in error path. - */ - btrfs_folio_inc_eb_refs(fs_info, folio); - spin_unlock(&mapping->i_private_lock); - WARN_ON(btrfs_folio_test_dirty(fs_info, folio, eb->start, eb->len)); /* |