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| author | Suparna Bhattacharya <suparna@in.ibm.com> | 2006-10-11 12:21:06 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-10-11 22:14:16 +0400 |
| commit | 471d4011a9862efff02094388b8fe8cd67683c38 (patch) | |
| tree | 7ec2cdd632cf4076517d3c81044643ac65528b9b /fs/ext4/extents.c | |
| parent | f65e6fba163dfd0f962efb7d8f5528b6872e2b15 (diff) | |
| download | linux-471d4011a9862efff02094388b8fe8cd67683c38.tar.xz | |
[PATCH] ext4: uninitialised extent handling
Make it possible to add file preallocation support in future as an RO_COMPAT
feature by recognizing uninitialized extents as holes and limiting extent
length to keep the top bit of ee_len free for marking uninitialized extents.
Signed-off-by: Suparna Bhattacharya <suparna@in.ibm.com>
Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: Dave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs/ext4/extents.c')
| -rw-r--r-- | fs/ext4/extents.c | 16 |
1 files changed, 16 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, != 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; |