From: "Amit K. Arora" Subject: [PATCH 3/5] ext4: Extent overlap bugfix Cc: linux-ext4@vger.kernel.org, suparna@in.ibm.com, cmm@us.ibm.com This is a fix for an extent-overlap bug. The fallocate() implementation on ext4 depends on this bugfix. Though this fix had been posted earlier, but because it is still not part of mainline code, I have attached it here too. Signed-off-by: Amit Arora --- fs/ext4/extents.c | 50 ++++++++++++++++++++++++++++++++++++++-- include/linux/ext4_fs_extents.h | 1 2 files changed, 49 insertions(+), 2 deletions(-) Index: linux-2.6.21/fs/ext4/extents.c =================================================================== --- linux-2.6.21.orig/fs/ext4/extents.c +++ linux-2.6.21/fs/ext4/extents.c @@ -1129,6 +1129,45 @@ ext4_can_extents_be_merged(struct inode } /* + * ext4_ext_check_overlap: + * check if a portion of the "newext" extent overlaps with an + * existing extent. + * + * If there is an overlap discovered, it updates the length of the newext + * such that there will be no overlap, and then returns 1. + * If there is no overlap found, it returns 0. + */ +unsigned int ext4_ext_check_overlap(struct inode *inode, + struct ext4_extent *newext, + struct ext4_ext_path *path) +{ + unsigned long b1, b2; + unsigned int depth, len1; + + b1 = le32_to_cpu(newext->ee_block); + len1 = le16_to_cpu(newext->ee_len); + depth = ext_depth(inode); + if (!path[depth].p_ext) + goto out; + b2 = le32_to_cpu(path[depth].p_ext->ee_block); + + /* get the next allocated block if the extent in the path + * is before the requested block(s) */ + if (b2 < b1) { + b2 = ext4_ext_next_allocated_block(path); + if (b2 == EXT_MAX_BLOCK) + goto out; + } + + if (b1 + len1 > b2) { + newext->ee_len = cpu_to_le16(b2 - b1); + return 1; + } +out: + return 0; +} + +/* * ext4_ext_insert_extent: * tries to merge requsted extent into the existing extent or * inserts requested extent as new one into the tree, @@ -2032,7 +2071,15 @@ int ext4_ext_get_blocks(handle_t *handle /* allocate new block */ goal = ext4_ext_find_goal(inode, path, iblock); - allocated = max_blocks; + + /* Check if we can really insert (iblock)::(iblock+max_blocks) extent */ + newex.ee_block = cpu_to_le32(iblock); + newex.ee_len = cpu_to_le16(max_blocks); + err = ext4_ext_check_overlap(inode, &newex, path); + if (err) + allocated = le16_to_cpu(newex.ee_len); + else + allocated = max_blocks; newblock = ext4_new_blocks(handle, inode, goal, &allocated, &err); if (!newblock) goto out2; @@ -2040,7 +2087,6 @@ int ext4_ext_get_blocks(handle_t *handle goal, newblock, allocated); /* try to insert new extent into found leaf and return */ - newex.ee_block = cpu_to_le32(iblock); ext4_ext_store_pblock(&newex, newblock); newex.ee_len = cpu_to_le16(allocated); err = ext4_ext_insert_extent(handle, inode, path, &newex); Index: linux-2.6.21/include/linux/ext4_fs_extents.h =================================================================== --- linux-2.6.21.orig/include/linux/ext4_fs_extents.h +++ linux-2.6.21/include/linux/ext4_fs_extents.h @@ -190,6 +190,7 @@ ext4_ext_invalidate_cache(struct inode * extern int ext4_extent_tree_init(handle_t *, struct inode *); extern int ext4_ext_calc_credits_for_insert(struct inode *, struct ext4_ext_path *); +extern unsigned int ext4_ext_check_overlap(struct inode *, struct ext4_extent *, struct ext4_ext_path *); extern int ext4_ext_insert_extent(handle_t *, struct inode *, struct ext4_ext_path *, struct ext4_extent *); extern int ext4_ext_walk_space(struct inode *, unsigned long, unsigned long, ext_prepare_callback, void *); extern struct ext4_ext_path * ext4_ext_find_extent(struct inode *, int, struct ext4_ext_path *); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/