diff options
| -rw-r--r-- | fs/ext4/extents.c | 187 |
1 files changed, 148 insertions, 39 deletions
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index d16f6b5..9ea1bc6 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -3775,6 +3775,7 @@ int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset, } return ret > 0 ? ret2 : ret; } + /* * Callback function called for each extent to gather FIEMAP information. */ @@ -3782,38 +3783,162 @@ static int ext4_ext_fiemap_cb(struct inode *inode, struct ext4_ext_path *path, struct ext4_ext_cache *newex, struct ext4_extent *ex, void *data) { - struct fiemap_extent_info *fieinfo = data; - unsigned char blksize_bits = inode->i_sb->s_blocksize_bits; __u64 logical; __u64 physical; __u64 length; + loff_t size; __u32 flags = 0; - int error; + int ret = 0; + struct fiemap_extent_info *fieinfo = data; + unsigned char blksize_bits; - logical = (__u64)newex->ec_block << blksize_bits; + blksize_bits = inode->i_sb->s_blocksize_bits; + logical = (__u64)newex->ec_block << blksize_bits; if (newex->ec_start == 0) { - pgoff_t offset; - struct page *page; + /* + * No extent in extent-tree contains block @newex->ec_start, + * then the block may stay in 1)a hole or 2)delayed-extent. + * + * Holes or delayed-extents are processed as follows. + * 1. lookup dirty pages with specified range in pagecache. + * If no page is got, then there is no delayed-extent and + * return with EXT_CONTINUE. + * 2. find the 1st mapped buffer, + * 3. check if the mapped buffer is both in the request range + * and a delayed buffer. If not, there is no delayed-extent, + * then return. + * 4. a delayed-extent is found, the extent will be collected. + */ + ext4_lblk_t end = 0; + pgoff_t last_offset; + pgoff_t offset; + pgoff_t index; + struct page **pages = NULL; struct buffer_head *bh = NULL; + struct buffer_head *head = NULL; + unsigned int nr_pages = PAGE_SIZE / sizeof(struct page *); + + pages = kmalloc(PAGE_SIZE, GFP_KERNEL); + if (pages == NULL) + return -ENOMEM; offset = logical >> PAGE_SHIFT; - page = find_get_page(inode->i_mapping, offset); - if (!page || !page_has_buffers(page)) - return EXT_CONTINUE; +repeat: + last_offset = offset; + head = NULL; + ret = find_get_pages_tag(inode->i_mapping, &offset, + PAGECACHE_TAG_DIRTY, nr_pages, pages); + + if (!(flags & FIEMAP_EXTENT_DELALLOC)) { + /* First time, try to find a mapped buffer. */ + if (ret == 0) { +out: + for (index = 0; index < ret; index++) + page_cache_release(pages[index]); + /* just a hole. */ + kfree(pages); + return EXT_CONTINUE; + } - bh = page_buffers(page); + /* Try to find the 1st mapped buffer. */ + end = ((__u64)pages[0]->index << PAGE_SHIFT) >> + blksize_bits; + if (!page_has_buffers(pages[0])) + goto out; + head = page_buffers(pages[0]); + if (!head) + goto out; - if (!bh) - return EXT_CONTINUE; + bh = head; + do { + if (buffer_mapped(bh)) { + /* get the 1st mapped buffer. */ + if (end > newex->ec_block + + newex->ec_len) + /* The buffer is out of + * the request range. + */ + goto out; + goto found_mapped_buffer; + } + bh = bh->b_this_page; + end++; + } while (bh != head); - if (buffer_delay(bh)) { - flags |= FIEMAP_EXTENT_DELALLOC; - page_cache_release(page); + /* No mapped buffer found. */ + goto out; } else { - page_cache_release(page); - return EXT_CONTINUE; + /*Find contiguous delayed buffers. */ + if (ret > 0 && pages[0]->index == last_offset) + head = page_buffers(pages[0]); + bh = head; + } + +found_mapped_buffer: + if (bh != NULL && buffer_delay(bh)) { + /* 1st or contiguous delayed buffer found. */ + if (!(flags & FIEMAP_EXTENT_DELALLOC)) { + /* + * 1st delayed buffer found, record + * the start of extent. + */ + flags |= FIEMAP_EXTENT_DELALLOC; + newex->ec_block = end; + logical = (__u64)end << blksize_bits; + } + /* Find contiguous delayed buffers. */ + do { + if (!buffer_delay(bh)) + goto found_delayed_extent; + bh = bh->b_this_page; + end++; + } while (bh != head); + + for (index = 1; index < ret; index++) { + if (!page_has_buffers(pages[index])) { + bh = NULL; + break; + } + head = page_buffers(pages[index]); + if (!head) { + bh = NULL; + break; + } + if (pages[index]->index != + pages[0]->index + index) { + /* Blocks are not contiguous. */ + bh = NULL; + break; + } + bh = head; + do { + if (!buffer_delay(bh)) + /* Delayed-extent ends. */ + goto found_delayed_extent; + bh = bh->b_this_page; + end++; + } while (bh != head); + } + } else if (!(flags & FIEMAP_EXTENT_DELALLOC)) + /* a hole found. */ + goto out; + +found_delayed_extent: + newex->ec_len = min(end - newex->ec_block, + (ext4_lblk_t)EXT_INIT_MAX_LEN); + if (ret == nr_pages && bh != NULL && + newex->ec_len < EXT_INIT_MAX_LEN && + buffer_delay(bh)) { + /* Have not collected an extent and continue. */ + for (index = 0; index < ret; index++) + page_cache_release(pages[index]); + goto repeat; } + + for (index = 0; index < ret; index++) + page_cache_release(pages[index]); + kfree(pages); } physical = (__u64)newex->ec_start << blksize_bits; @@ -3822,32 +3947,16 @@ static int ext4_ext_fiemap_cb(struct inode *inode, struct ext4_ext_path *path, if (ex && ext4_ext_is_uninitialized(ex)) flags |= FIEMAP_EXTENT_UNWRITTEN; - /* - * If this extent reaches EXT_MAX_BLOCK, it must be last. - * - * Or if ext4_ext_next_allocated_block is EXT_MAX_BLOCK, - * this also indicates no more allocated blocks. - * - * XXX this might miss a single-block extent at EXT_MAX_BLOCK - */ - if (ext4_ext_next_allocated_block(path) == EXT_MAX_BLOCK || - newex->ec_block + newex->ec_len - 1 == EXT_MAX_BLOCK) { - loff_t size = i_size_read(inode); - loff_t bs = EXT4_BLOCK_SIZE(inode->i_sb); - + size = i_size_read(inode); + if (logical + length >= size) flags |= FIEMAP_EXTENT_LAST; - if ((flags & FIEMAP_EXTENT_DELALLOC) && - logical+length > size) - length = (size - logical + bs - 1) & ~(bs-1); - } - error = fiemap_fill_next_extent(fieinfo, logical, physical, + ret = fiemap_fill_next_extent(fieinfo, logical, physical, length, flags); - if (error < 0) - return error; - if (error == 1) + if (ret < 0) + return ret; + if (ret == 1) return EXT_BREAK; - return EXT_CONTINUE; } |