[PATCH 2/8] nowait aio: Return if cannot get hold of i_rwsem

[Goldwyn Rodrigues]

From: Goldwyn Rodrigues <rgold...@suse.com>

A failure to lock i_rwsem would mean there is I/O being performed
by another thread. So, let's bail.

Signed-off-by: Goldwyn Rodrigues <rgold...@suse.com>
---
 mm/filemap.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 3f9afde..78dd50e 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2973,7 +2973,12 @@ ssize_t generic_file_write_iter(struct kiocb *iocb, 
struct iov_iter *from)
        struct inode *inode = file->f_mapping->host;
        ssize_t ret;
 
-       inode_lock(inode);
+       if (!inode_trylock(inode)) {
+               /* Don't sleep on inode rwsem */
+               if (iocb->ki_flags & IOCB_NOWAIT)
+                       return -EAGAIN;
+               inode_lock(inode);
+       }
        ret = generic_write_checks(iocb, from);
        if (ret > 0)
                ret = __generic_file_write_iter(iocb, from);
-- 
2.10.2

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