diff options
| -rw-r--r-- | fs/ext4/extents.c | 16 | ||||
| -rw-r--r-- | include/linux/ext4_fs_extents.h | 2 |
2 files changed, 18 insertions, 0 deletions
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 4a13b56e154..32526061a17 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -1082,6 +1082,13 @@ ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1, != le32_to_cpu(ex2->ee_block)) return 0; + /* + * To allow future support for preallocated extents to be added + * as an RO_COMPAT feature, refuse to merge to extents if + * can result in the top bit of ee_len being set + */ + if (le16_to_cpu(ex1->ee_len) + le16_to_cpu(ex2->ee_len) > EXT_MAX_LEN) + return 0; #ifdef AGRESSIVE_TEST if (le16_to_cpu(ex1->ee_len) >= 4) return 0; @@ -1944,6 +1951,15 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode, unsigned long ee_block = le32_to_cpu(ex->ee_block); ext4_fsblk_t ee_start = ext_pblock(ex); unsigned short ee_len = le16_to_cpu(ex->ee_len); + + /* + * Allow future support for preallocated extents to be added + * as an RO_COMPAT feature: + * Uninitialized extents are treated as holes, except that + * we avoid (fail) allocating new blocks during a write. + */ + if (ee_len > EXT_MAX_LEN) + goto out2; /* if found exent covers block, simple return it */ if (iblock >= ee_block && iblock < ee_block + ee_len) { newblock = iblock - ee_block + ee_start; diff --git a/include/linux/ext4_fs_extents.h b/include/linux/ext4_fs_extents.h index facc76684d4..0eba0acf6ba 100644 --- a/include/linux/ext4_fs_extents.h +++ b/include/linux/ext4_fs_extents.h @@ -141,6 +141,8 @@ typedef int (*ext_prepare_callback)(struct inode *, struct ext4_ext_path *, #define EXT_MAX_BLOCK 0xffffffff +#define EXT_MAX_LEN ((1UL << 15) - 1) + #define EXT_FIRST_EXTENT(__hdr__) \ ((struct ext4_extent *) (((char *) (__hdr__)) + \ |