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authorEryu Guan <eguan@redhat.com>2017-09-21 11:26:18 -0700
committerDarrick J. Wong <darrick.wong@oracle.com>2017-09-26 10:55:19 -0700
commitee70daaba82d70766d0723b743d9fdeb3b06102a (patch)
tree4ebdc08030551694139a99df64765a723fd08d5b /fs/xfs/xfs_file.c
parent546e7be8244dc050effef0555df5b8d94d10dafc (diff)
xfs: update i_size after unwritten conversion in dio completion
Since commit d531d91d6990 ("xfs: always use unwritten extents for direct I/O writes"), we start allocating unwritten extents for all direct writes to allow appending aio in XFS. But for dio writes that could extend file size we update the in-core inode size first, then convert the unwritten extents to real allocations at dio completion time in xfs_dio_write_end_io(). Thus a racing direct read could see the new i_size and find the unwritten extents first and read zeros instead of actual data, if the direct writer also takes a shared iolock. Fix it by updating the in-core inode size after the unwritten extent conversion. To do this, introduce a new boolean argument to xfs_iomap_write_unwritten() to tell if we want to update in-core i_size or not. Suggested-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Signed-off-by: Eryu Guan <eguan@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Diffstat (limited to 'fs/xfs/xfs_file.c')
-rw-r--r--fs/xfs/xfs_file.c33
1 files changed, 19 insertions, 14 deletions
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 350b6d43ba23..309e26c9dddb 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -434,7 +434,6 @@ xfs_dio_write_end_io(
struct inode *inode = file_inode(iocb->ki_filp);
struct xfs_inode *ip = XFS_I(inode);
loff_t offset = iocb->ki_pos;
- bool update_size = false;
int error = 0;
trace_xfs_end_io_direct_write(ip, offset, size);
@@ -445,6 +444,21 @@ xfs_dio_write_end_io(
if (size <= 0)
return size;
+ if (flags & IOMAP_DIO_COW) {
+ error = xfs_reflink_end_cow(ip, offset, size);
+ if (error)
+ return error;
+ }
+
+ /*
+ * Unwritten conversion updates the in-core isize after extent
+ * conversion but before updating the on-disk size. Updating isize any
+ * earlier allows a racing dio read to find unwritten extents before
+ * they are converted.
+ */
+ if (flags & IOMAP_DIO_UNWRITTEN)
+ return xfs_iomap_write_unwritten(ip, offset, size, true);
+
/*
* We need to update the in-core inode size here so that we don't end up
* with the on-disk inode size being outside the in-core inode size. We
@@ -459,20 +473,11 @@ xfs_dio_write_end_io(
spin_lock(&ip->i_flags_lock);
if (offset + size > i_size_read(inode)) {
i_size_write(inode, offset + size);
- update_size = true;
- }
- spin_unlock(&ip->i_flags_lock);
-
- if (flags & IOMAP_DIO_COW) {
- error = xfs_reflink_end_cow(ip, offset, size);
- if (error)
- return error;
- }
-
- if (flags & IOMAP_DIO_UNWRITTEN)
- error = xfs_iomap_write_unwritten(ip, offset, size);
- else if (update_size)
+ spin_unlock(&ip->i_flags_lock);
error = xfs_setfilesize(ip, offset, size);
+ } else {
+ spin_unlock(&ip->i_flags_lock);
+ }
return error;
}