xfs: serialize unaligned dio writes against all other dio writes

[linux.git] / fs / xfs / xfs_file.c

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 1f2e2845eb76c2c78a932c913057e1028cec2f05..a7ceae90110eded646f13acf4314131574d46a69 100644 (file)
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -529,18 +529,17 @@ xfs_file_dio_aio_write(
        count = iov_iter_count(from);
 
        /*
-        * If we are doing unaligned IO, wait for all other IO to drain,
-        * otherwise demote the lock if we had to take the exclusive lock
-        * for other reasons in xfs_file_aio_write_checks.
+        * If we are doing unaligned IO, we can't allow any other overlapping IO
+        * in-flight at the same time or we risk data corruption. Wait for all
+        * other IO to drain before we submit. If the IO is aligned, demote the
+        * iolock if we had to take the exclusive lock in
+        * xfs_file_aio_write_checks() for other reasons.
         */
        if (unaligned_io) {
-               /* If we are going to wait for other DIO to finish, bail */
-               if (iocb->ki_flags & IOCB_NOWAIT) {
-                       if (atomic_read(&inode->i_dio_count))
-                               return -EAGAIN;
-               } else {
-                       inode_dio_wait(inode);
-               }
+               /* unaligned dio always waits, bail */
+               if (iocb->ki_flags & IOCB_NOWAIT)
+                       return -EAGAIN;
+               inode_dio_wait(inode);
        } else if (iolock == XFS_IOLOCK_EXCL) {
                xfs_ilock_demote(ip, XFS_IOLOCK_EXCL);
                iolock = XFS_IOLOCK_SHARED;
@@ -548,6 +547,14 @@ xfs_file_dio_aio_write(
 
        trace_xfs_file_direct_write(ip, count, iocb->ki_pos);
        ret = iomap_dio_rw(iocb, from, &xfs_iomap_ops, xfs_dio_write_end_io);
+
+       /*
+        * If unaligned, this is the only IO in-flight. If it has not yet
+        * completed, wait on it before we release the iolock to prevent
+        * subsequent overlapping IO.
+        */
+       if (ret == -EIOCBQUEUED && unaligned_io)
+               inode_dio_wait(inode);
 out:
        xfs_iunlock(ip, iolock);