From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
Return EAGAIN if any of the following checks fail for direct I/O:
+ i_rwsem is lockable
+ Writing beyond end of file (will trigger allocation)
+ Blocks are allocated at the write location
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
---
fs/ext4/file.c | 28 ++++++++++++++++++++++------
1 file changed, 22 insertions(+), 6 deletions(-)
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 2a822d3..c8d1e41 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -93,11 +93,16 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
struct inode *inode = file_inode(iocb->ki_filp);
int o_direct = iocb->ki_flags & IOCB_DIRECT;
+ int nonblocking = iocb->ki_flags & IOCB_NONBLOCKING;
int unaligned_aio = 0;
int overwrite = 0;
ssize_t ret;
- inode_lock(inode);
+ if (o_direct && nonblocking) {
+ if (!inode_trylock(inode))
+ return -EAGAIN;
+ } else
+ inode_lock(inode);
ret = generic_write_checks(iocb, from);
if (ret <= 0)
goto out;
@@ -132,12 +137,18 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
if (o_direct) {
size_t length = iov_iter_count(from);
loff_t pos = iocb->ki_pos;
+ unsigned int blkbits = inode->i_blkbits;
+
+ if (nonblocking
+ && (pos + length > EXT4_BLOCK_ALIGN(i_size_read(inode), blkbits))) {
+ ret = -EAGAIN;
+ goto out;
+ }
/* check whether we do a DIO overwrite or not */
- if (ext4_should_dioread_nolock(inode) && !unaligned_aio &&
- pos + length <= i_size_read(inode)) {
+ if ((ext4_should_dioread_nolock(inode) && !unaligned_aio &&
+ pos + length <= i_size_read(inode)) || nonblocking) {
struct ext4_map_blocks map;
- unsigned int blkbits = inode->i_blkbits;
int err, len;
map.m_lblk = pos >> blkbits;
@@ -157,8 +168,13 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
* non-flags are returned. So we should check
* these two conditions.
*/
- if (err == len && (map.m_flags & EXT4_MAP_MAPPED))
- overwrite = 1;
+ if (err == len) {
+ if (map.m_flags & EXT4_MAP_MAPPED)
+ overwrite = 1;
+ } else if (nonblocking) {
+ ret = -EAGAIN;
+ goto out;
+ }
}
}
--
2.10.2
