On 28 Jul 2016, at 14:47, Trond Myklebust wrote:
> On Thu, 2016-07-28 at 14:41 -0400, Benjamin Coddington wrote:
>> Block/SCSI layout write completion may add committable extents to the
>> extent tree before updating the layout's last-written byte under the
>> inode
>> lock. If a sync happens before this value is updated, then
>> prepare_layoutcommit may find and encode these extents which would
>> produce
>> a LAYOUTCOMMIT request whose encoded extents are larger than the
>> request's
>> loca_length.
>>
>> Fix this by updating the last_write_offset to match the currently
>> encoded
>> extents.
>>
>> Signed-off-by: Benjamin Coddington <bcodding@xxxxxxxxxx>
>> ---
>> fs/nfs/blocklayout/extent_tree.c | 6 ++++--
>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/nfs/blocklayout/extent_tree.c
>> b/fs/nfs/blocklayout/extent_tree.c
>> index 992bcb19c11e..18ae1fd2175e 100644
>> --- a/fs/nfs/blocklayout/extent_tree.c
>> +++ b/fs/nfs/blocklayout/extent_tree.c
>> @@ -518,7 +518,7 @@ static __be32 *encode_scsi_range(struct
>> pnfs_block_extent *be, __be32 *p)
>> }
>>
>> static int ext_tree_encode_commit(struct pnfs_block_layout *bl,
>> __be32 *p,
>> - size_t buffer_size, size_t *count)
>> + size_t buffer_size, size_t *count, __u64 *lastbyte)
>> {
>> struct pnfs_block_extent *be;
>> int ret = 0;
>> @@ -541,6 +541,8 @@ static int ext_tree_encode_commit(struct
>> pnfs_block_layout *bl, __be32 *p,
>> else
>> p = encode_block_extent(be, p);
>> be->be_tag = EXTENT_COMMITTING;
>> + if ((ext_f_end(be) << SECTOR_SHIFT) - 1 > *lastbyte)
>> + *lastbyte = (ext_f_end(be) << SECTOR_SHIFT)
>> - 1;
>
> Won't this cause the file size to be always sector aligned on the
> server? I was assuming that we would have to store the lastbyte
> atomically with setting up the commit in ext_tree_mark_written().
You're right. It is incorrect. I'll fix it.
Ben
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