From: Jan Kara <[email protected]>

commit 0b3171b6d195637f84ddf8b59bae818ea20bc8ac upstream.

Since commit 378f32bab371 ("ext4: introduce direct I/O write using iomap
infrastructure") we don't properly bail out of RWF_NOWAIT direct IO
write if underlying blocks are not allocated. Also
ext4_dio_write_checks() does not honor RWF_NOWAIT when re-acquiring
i_rwsem. Fix both issues.

Fixes: 378f32bab371 ("ext4: introduce direct I/O write using iomap 
infrastructure")
Cc: [email protected]
Reported-by: Filipe Manana <[email protected]>
Signed-off-by: Jan Kara <[email protected]>
Reviewed-by: Ritesh Harjani <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Theodore Ts'o <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 fs/ext4/file.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -428,6 +428,10 @@ restart:
         */
        if (*ilock_shared && (!IS_NOSEC(inode) || *extend ||
             !ext4_overwrite_io(inode, offset, count))) {
+               if (iocb->ki_flags & IOCB_NOWAIT) {
+                       ret = -EAGAIN;
+                       goto out;
+               }
                inode_unlock_shared(inode);
                *ilock_shared = false;
                inode_lock(inode);


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