Messages in this thread Patch in this message | | | Date | Wed, 15 Aug 2007 17:52:28 +0400 | From | Dmitry Monakhov <> | Subject | [PATCH] mm: fix blkdev size calculation in generic_write_checks |
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Currently block device size calculated regardless its bd_block_size. This may result attempt to write outside block device if i_size not aligned to bdev->bd_block_size and result in EIO.
#### TEST_CASE_BEGIN # fdisk -l /dev/sdc Disk /dev/sdc: 36.7 GB, 36703918080 bytes 255 heads, 63 sectors/track, 4462 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System /dev/sdc1 * 1 254 2040223+ 83 Ldinux /dev/sdc2 255 379 1004062+ 83 Linux #### #### /dev/sdc2 size not aligned to 4K
#### at this time bd_block_size == 512 so generic_write_check #### performed correctly # dd if=/dev/zero of=/dev/sdc2 bs=1k count=7 seek=1004058 dd: writing `/dev/sdc2': No space left on device 5+0 records in 4+0 records out
#### this bdev contain ext4fs with blksize = 4K # mount /dev/sdc2 /mnt/ #### after we mounted this bdev bd_block_size == fsblksize == 4K
#### the same write operation failed with EIO # dd if=/dev/zero of=/dev/sdc2 bs=1k count=7 seek=1004058 dd: writing `/dev/sdc2': Input/output error 3+0 records in 2+0 records out #### Attempt to write whole fsblock result write access outside #### blkdevice and cause -EIO (returned by blkdev_get_block) #### TEST_CASE_END
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org> --- mm/filemap.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/mm/filemap.c b/mm/filemap.c index 2c8776b..a23ee8a 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1867,9 +1867,11 @@ inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, i } else { #ifdef CONFIG_BLOCK loff_t isize; + unsigned int blksize; if (bdev_read_only(I_BDEV(inode))) return -EPERM; - isize = i_size_read(inode); + blksize = block_size(I_BDEV(inode)); + isize = i_size_read(inode) & ~(blksize - 1); if (*pos >= isize) { if (*count || *pos > isize) return -ENOSPC; -- 1.5.2.2
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