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ext4: fix ZERO_RANGE bug hidden by flag aliasing 

We accidently aliased EXT4_EX_NOCACHE and EXT4_GET_CONVERT_UNWRITTEN
falgs, which apparently was hiding a bug that was unmasked when this
flag aliasing issue was addressed (see the subsequent commit).  The
reproduction case was:

   fsx -N 10000 -l 500000 -r 4096 -t 4096 -w 4096 -Z -R -W /vdb/junk

... which would cause fsx to report corruption in the data file.

The fix we have is a bit of an overkill, but I'd much rather be
conservative for now, and we can optimize ZERO_RANGE_FL handling
later.  The fact that we need to zap the extent_status cache for the
inode is unfortunate, but correctness is far more important than
performance.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: Namjae Jeon <namjae.jeon@samsung.com>
This commit is contained in:
Theodore Ts'o 2014-09-01 14:32:09 -04:00
parent 19008f6dfa
commit 713e8dde3e
1 changed files with 15 additions and 8 deletions
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23
fs/ext4/extents.c
View File

@ -4802,7 +4802,8 @@ static long ext4_zero_range(struct file *file, loff_t offset,
max_blocks -= lblk; max_blocks -= lblk;
flags = EXT4_GET_BLOCKS_CREATE_UNWRIT_EXT | flags = EXT4_GET_BLOCKS_CREATE_UNWRIT_EXT |
EXT4_GET_BLOCKS_CONVERT_UNWRITTEN; EXT4_GET_BLOCKS_CONVERT_UNWRITTEN |
EXT4_EX_NOCACHE;
if (mode & FALLOC_FL_KEEP_SIZE) if (mode & FALLOC_FL_KEEP_SIZE)
flags |= EXT4_GET_BLOCKS_KEEP_SIZE; flags |= EXT4_GET_BLOCKS_KEEP_SIZE;
@ -4840,17 +4841,23 @@ static long ext4_zero_range(struct file *file, loff_t offset,
ext4_inode_block_unlocked_dio(inode); ext4_inode_block_unlocked_dio(inode);
inode_dio_wait(inode); inode_dio_wait(inode);
/*
* Remove entire range from the extent status tree.
*/
ret = ext4_es_remove_extent(inode, lblk, max_blocks);
if (ret)
goto out_dio;
ret = ext4_alloc_file_blocks(file, lblk, max_blocks, new_size, ret = ext4_alloc_file_blocks(file, lblk, max_blocks, new_size,
flags, mode); flags, mode);
if (ret) if (ret)
goto out_dio; goto out_dio;
/*
* Remove entire range from the extent status tree.
*
* ext4_es_remove_extent(inode, lblk, max_blocks) is
* NOT sufficient. I'm not sure why this is the case,
* but let's be conservative and remove the extent
* status tree for the entire inode. There should be
* no outstanding delalloc extents thanks to the
* filemap_write_and_wait_range() call above.
*/
ret = ext4_es_remove_extent(inode, 0, EXT_MAX_BLOCKS);
if (ret)
goto out_dio;
} }
if (!partial_begin && !partial_end) if (!partial_begin && !partial_end)
goto out_dio; goto out_dio;