On 06/03/2024 21:22, Dave Chinner wrote:
On Mon, Mar 04, 2024 at 01:04:27PM +0000, John Garry wrote:
Validate that an atomic write adheres to length/offset rules. Since we
require extent alignment for atomic writes, this effectively also enforces
that the BIO which iomap produces is aligned.
Signed-off-by: John Garry<john.g.garry@xxxxxxxxxx>
---
fs/xfs/xfs_file.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index d0bd9d5f596c..cecc5428fd7c 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -709,11 +709,20 @@ xfs_file_dio_write(
struct kiocb *iocb,
struct iov_iter *from)
{
- struct xfs_inode *ip = XFS_I(file_inode(iocb->ki_filp));
+ struct inode *inode = file_inode(iocb->ki_filp);
+ struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
struct xfs_buftarg *target = xfs_inode_buftarg(ip);
size_t count = iov_iter_count(from);
+ if (iocb->ki_flags & IOCB_ATOMIC) {
+ if (!generic_atomic_write_valid(iocb->ki_pos, from,
+ i_blocksize(inode),
a.k.a. mp->m_bsize. If you use that here, then the need for the VFS
inode goes away, too.
ok
+ XFS_FSB_TO_B(mp, xfs_get_extsz(ip)))) {
+ return -EINVAL;
+ }
+ }
Also, I think the checks are the wrong way around here. We can only
do IOCB_ATOMIC IO on force aligned/atomic write inodes, so shouldn't
we be checking that first,
We are checking that, but not here.
In 14/14, we only set FMODE_CAN_ATOMIC_WRITE for when
xfs_inode_has_atomicwrites() is true, and only when
FMODE_CAN_ATOMIC_WRITE is set can we get this far.
I don't see a point in duplicating this xfs_inode_has_atomicwrites()
check, so I will make the commit message clearer on this - ok? Or add a
comment.
then basing the rest of the checks on the
assumption that atomic writes are allowed and have been set up
correctly on the inode? i.e.
if (iocb->ki_flags & IOCB_ATOMIC) {
if (!xfs_inode_has_atomicwrites(ip))
return -EINVAL;
if (!generic_atomic_write_valid(iocb->ki_pos, from,
mp->m_bsize, ip->i_extsize))
return -EINVAL;
}
because xfs_inode_has_atomicwrites() implies ip->i_extsize has been
set to the required atomic IO size?
I was not too comfortable using ip->i_extsize, as this can be set
without forcealign being set. I know that we would not get this far
without forcealign (being set).
Having said that, I don't like all the xfs_get_extsz() calls, so
something better is required. Let me know you you think.
Thanks,
John
