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-rw-r--r--fs/ext4/extents.c16
-rw-r--r--include/linux/ext4_fs_extents.h2
2 files changed, 18 insertions, 0 deletions
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 4a13b56e1540..32526061a17d 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,
1082 != le32_to_cpu(ex2->ee_block)) 1082 != le32_to_cpu(ex2->ee_block))
1083 return 0; 1083 return 0;
1084 1084
1085 /*
1086 * To allow future support for preallocated extents to be added
1087 * as an RO_COMPAT feature, refuse to merge to extents if
1088 * can result in the top bit of ee_len being set
1089 */
1090 if (le16_to_cpu(ex1->ee_len) + le16_to_cpu(ex2->ee_len) > EXT_MAX_LEN)
1091 return 0;
1085#ifdef AGRESSIVE_TEST 1092#ifdef AGRESSIVE_TEST
1086 if (le16_to_cpu(ex1->ee_len) >= 4) 1093 if (le16_to_cpu(ex1->ee_len) >= 4)
1087 return 0; 1094 return 0;
@@ -1944,6 +1951,15 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
1944 unsigned long ee_block = le32_to_cpu(ex->ee_block); 1951 unsigned long ee_block = le32_to_cpu(ex->ee_block);
1945 ext4_fsblk_t ee_start = ext_pblock(ex); 1952 ext4_fsblk_t ee_start = ext_pblock(ex);
1946 unsigned short ee_len = le16_to_cpu(ex->ee_len); 1953 unsigned short ee_len = le16_to_cpu(ex->ee_len);
1954
1955 /*
1956 * Allow future support for preallocated extents to be added
1957 * as an RO_COMPAT feature:
1958 * Uninitialized extents are treated as holes, except that
1959 * we avoid (fail) allocating new blocks during a write.
1960 */
1961 if (ee_len > EXT_MAX_LEN)
1962 goto out2;
1947 /* if found exent covers block, simple return it */ 1963 /* if found exent covers block, simple return it */
1948 if (iblock >= ee_block && iblock < ee_block + ee_len) { 1964 if (iblock >= ee_block && iblock < ee_block + ee_len) {
1949 newblock = iblock - ee_block + ee_start; 1965 newblock = iblock - ee_block + ee_start;
diff --git a/include/linux/ext4_fs_extents.h b/include/linux/ext4_fs_extents.h
index facc76684d4f..0eba0acf6ba6 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 *,
141 141
142#define EXT_MAX_BLOCK 0xffffffff 142#define EXT_MAX_BLOCK 0xffffffff
143 143
144#define EXT_MAX_LEN ((1UL << 15) - 1)
145
144 146
145#define EXT_FIRST_EXTENT(__hdr__) \ 147#define EXT_FIRST_EXTENT(__hdr__) \
146 ((struct ext4_extent *) (((char *) (__hdr__)) + \ 148 ((struct ext4_extent *) (((char *) (__hdr__)) + \