From f81db56f2fd6dc16efeaec2961121244765a1f11 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Stefan=20Br=C3=BCns?= Date: Sat, 5 Nov 2016 22:17:14 +0100 Subject: ext4: Fix handling of sparse files MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit A sparse file may have regions not mapped by any extents, at the start or at the end of the file, or anywhere between, thus not finding a matching extent region is never an error. Found by python filesystem tests. Signed-off-by: Stefan Brüns --- fs/ext4/ext4_common.c | 31 +++++++++++++++---------------- 1 file changed, 15 insertions(+), 16 deletions(-) (limited to 'fs/ext4') diff --git a/fs/ext4/ext4_common.c b/fs/ext4/ext4_common.c index 4248ac1dcf..bfebe7e379 100644 --- a/fs/ext4/ext4_common.c +++ b/fs/ext4/ext4_common.c @@ -1617,12 +1617,13 @@ long int read_allocated_block(struct ext2_inode *inode, int fileblock) - get_fs()->dev_desc->log2blksz; if (le32_to_cpu(inode->flags) & EXT4_EXTENTS_FL) { + long int startblock, endblock; char *buf = zalloc(blksz); if (!buf) return -ENOMEM; struct ext4_extent_header *ext_block; struct ext4_extent *extent; - int i = -1; + int i; ext_block = ext4fs_get_extent_block(ext4fs_root, buf, (struct ext4_extent_header *) @@ -1636,28 +1637,26 @@ long int read_allocated_block(struct ext2_inode *inode, int fileblock) extent = (struct ext4_extent *)(ext_block + 1); - do { - i++; - if (i >= le16_to_cpu(ext_block->eh_entries)) - break; - } while (fileblock >= le32_to_cpu(extent[i].ee_block)); - if (--i >= 0) { - fileblock -= le32_to_cpu(extent[i].ee_block); - if (fileblock >= le16_to_cpu(extent[i].ee_len)) { + for (i = 0; i < le16_to_cpu(ext_block->eh_entries); i++) { + startblock = le32_to_cpu(extent[i].ee_block); + endblock = startblock + le16_to_cpu(extent[i].ee_len); + + if (startblock > fileblock) { + /* Sparse file */ free(buf); return 0; - } - start = le16_to_cpu(extent[i].ee_start_hi); - start = (start << 32) + + } else if (fileblock < endblock) { + start = le16_to_cpu(extent[i].ee_start_hi); + start = (start << 32) + le32_to_cpu(extent[i].ee_start_lo); - free(buf); - return fileblock + start; + free(buf); + return (fileblock - startblock) + start; + } } - printf("Extent Error\n"); free(buf); - return -1; + return 0; } /* Direct blocks. */ -- cgit v1.2.3