On 2011-08-31, at 12:49 PM, Allison Henderson wrote:
> On 08/30/2011 05:31 PM, Andreas Dilger wrote:
>> On 2011-08-30, at 6:28 PM, Allison Henderson wrote:
>>> This patch modifies the fallocate routine to lock i_mutex during
>>> the punch hole operation.
>>>
>>> Yongqiang noticed that the vfs layer locks i_mutex for truncate,
>>> but not fallocate, so the fallocate routine will need to take
>>> care of locking i_mutex. Otherwise a page may be mapped after
>>> punch hole has released the pages, but before i_data_sem is
>>> locked to release the blocks in the extent tree.
>>
>> If the VFS is locking i_mutex for truncate, shouldn't the locking for
>> fallocate() also be done in the VFS?
>
> Alrighty, I will do some poking around with this idea first. I dont know if other files systems are already locking i_mutex during fallocate, and it may be the case that not all filesystems need i_mutex locked for fallocate. So I'll do a little research first, but I will post back with what I find. Thx!
Probably a good idea to bring up this issue on linux-fsdevel.
>>> Signed-off-by: Allison Henderson<achender@xxxxxxxxxxxxxxxxxx>
>>> ---
>>> :100644 100644 9124cd2... 007fb08... M fs/ext4/extents.c
>>> fs/ext4/extents.c | 10 +++++++---
>>> 1 files changed, 7 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
>>> index 9124cd2..007fb08 100644
>>> --- a/fs/ext4/extents.c
>>> +++ b/fs/ext4/extents.c
>>> @@ -3774,8 +3774,13 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
>>> if (mode& ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
>>> return -EOPNOTSUPP;
>>>
>>> - if (mode& FALLOC_FL_PUNCH_HOLE)
>>> - return ext4_punch_hole(file, offset, len);
>>> + mutex_lock(&inode->i_mutex);
>>> +
>>> + if (mode& FALLOC_FL_PUNCH_HOLE) {
>>> + ret = ext4_punch_hole(file, offset, len);
>>> + mutex_unlock(&inode->i_mutex);
>>> + return ret;
>>> + }
>>>
>>> trace_ext4_fallocate_enter(inode, offset, len, mode);
>>> map.m_lblk = offset>> blkbits;
>>> @@ -3789,7 +3794,6 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
>>> * credits to insert 1 extent into extent tree
>>> */
>>> credits = ext4_chunk_trans_blocks(inode, max_blocks);
>>> - mutex_lock(&inode->i_mutex);
>>> ret = inode_newsize_ok(inode, (len + offset));
>>> if (ret) {
>>> mutex_unlock(&inode->i_mutex);
>>> --
>>> 1.7.1
>>>
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
>>> the body of a message to majordomo@xxxxxxxxxxxxxxx
>>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>>
>>
>> Cheers, Andreas
>>
>>
>>
>>
>>
>
Cheers, Andreas
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
