From: Goldwyn Rodrigues <rgoldwyn@suse.de>
To: linux-fsdevel@vger.kernel.org
Cc: jack@suse.com, hch@infradead.org, linux-block@vger.kernel.org,
linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org,
linux-xfs@vger.kernel.org, sagi@grimberg.me, avi@scylladb.com,
axboe@kernel.dk, linux-api@vger.kernel.org, willy@infradead.org,
Goldwyn Rodrigues <rgoldwyn@suse.com>
Subject: [PATCH 6/8] nowait aio: ext4
Date: Wed, 15 Mar 2017 16:51:05 -0500 [thread overview]
Message-ID: <20170315215107.5628-7-rgoldwyn@suse.de> (raw)
In-Reply-To: <20170315215107.5628-1-rgoldwyn@suse.de>
From: Goldwyn Rodrigues <rgoldwyn@suse.com>
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 not allocated at the write location
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
---
fs/ext4/file.c | 48 +++++++++++++++++++++++++++++++-----------------
1 file changed, 31 insertions(+), 17 deletions(-)
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 8210c1f..e223b9f 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -127,27 +127,22 @@ ext4_unaligned_aio(struct inode *inode, struct iov_iter *from, loff_t pos)
return 0;
}
-/* Is IO overwriting allocated and initialized blocks? */
-static bool ext4_overwrite_io(struct inode *inode, loff_t pos, loff_t len)
+/* Are IO blocks allocated */
+static bool ext4_blocks_mapped(struct inode *inode, loff_t pos, loff_t len,
+ struct ext4_map_blocks *map)
{
- struct ext4_map_blocks map;
unsigned int blkbits = inode->i_blkbits;
int err, blklen;
if (pos + len > i_size_read(inode))
return false;
- map.m_lblk = pos >> blkbits;
- map.m_len = EXT4_MAX_BLOCKS(len, pos, blkbits);
- blklen = map.m_len;
+ map->m_lblk = pos >> blkbits;
+ map->m_len = EXT4_MAX_BLOCKS(len, pos, blkbits);
+ blklen = map->m_len;
- err = ext4_map_blocks(NULL, inode, &map, 0);
- /*
- * 'err==len' means that all of the blocks have been preallocated,
- * regardless of whether they have been initialized or not. To exclude
- * unwritten extents, we need to check m_flags.
- */
- return err == blklen && (map.m_flags & EXT4_MAP_MAPPED);
+ err = ext4_map_blocks(NULL, inode, map, 0);
+ return err == blklen;
}
static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from)
@@ -204,6 +199,7 @@ 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 nowait = iocb->ki_flags & IOCB_NOWAIT;
int unaligned_aio = 0;
int overwrite = 0;
ssize_t ret;
@@ -216,7 +212,13 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
return ext4_dax_write_iter(iocb, from);
#endif
- inode_lock(inode);
+ if (o_direct && nowait) {
+ if (!inode_trylock(inode))
+ return -EAGAIN;
+ } else {
+ inode_lock(inode);
+ }
+
ret = ext4_write_checks(iocb, from);
if (ret <= 0)
goto out;
@@ -235,9 +237,21 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
iocb->private = &overwrite;
/* Check whether we do a DIO overwrite or not */
- if (o_direct && ext4_should_dioread_nolock(inode) && !unaligned_aio &&
- ext4_overwrite_io(inode, iocb->ki_pos, iov_iter_count(from)))
- overwrite = 1;
+ if (o_direct && !unaligned_aio) {
+ struct ext4_map_blocks map;
+ if (ext4_blocks_mapped(inode, iocb->ki_pos,
+ iov_iter_count(from), &map)) {
+ /* To exclude unwritten extents, we need to check
+ * m_flags.
+ */
+ if (ext4_should_dioread_nolock(inode) &&
+ (map.m_flags & EXT4_MAP_MAPPED))
+ overwrite = 1;
+ } else if (iocb->ki_flags & IOCB_NOWAIT) {
+ ret = -EAGAIN;
+ goto out;
+ }
+ }
ret = __generic_file_write_iter(iocb, from);
inode_unlock(inode);
--
2.10.2
next prev parent reply other threads:[~2017-03-15 21:51 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-15 21:50 [PATCH 0/8 v3] No wait AIO Goldwyn Rodrigues
2017-03-15 21:51 ` [PATCH 1/8] nowait aio: Introduce IOCB_RW_FLAG_NOWAIT Goldwyn Rodrigues
2017-03-15 21:51 ` [PATCH 2/8] nowait aio: Return if cannot get hold of i_rwsem Goldwyn Rodrigues
2017-03-15 21:51 ` [PATCH 3/8] nowait aio: return if direct write will trigger writeback Goldwyn Rodrigues
2017-03-16 13:08 ` Matthew Wilcox
2017-03-16 13:46 ` Goldwyn Rodrigues
2017-03-16 13:20 ` Matthew Wilcox
[not found] ` <20170316132052.GG4033-PfSpb0PWhxZc2C7mugBRk2EX/6BAtgUQ@public.gmane.org>
2017-03-16 13:46 ` Goldwyn Rodrigues
2017-03-15 21:51 ` [PATCH 4/8] nowait-aio: Introduce IOMAP_NOWAIT Goldwyn Rodrigues
2017-03-15 21:51 ` [PATCH 5/8] nowait aio: return on congested block device Goldwyn Rodrigues
[not found] ` <20170315215107.5628-6-rgoldwyn-l3A5Bk7waGM@public.gmane.org>
2017-03-16 14:33 ` Jens Axboe
2017-03-17 2:03 ` Ming Lei
2017-03-17 12:23 ` Goldwyn Rodrigues
[not found] ` <eee4683d-9f44-434f-b97f-b0b24c7b3dab-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org>
2017-03-24 11:32 ` Goldwyn Rodrigues
2017-03-24 14:39 ` Jens Axboe
2017-03-16 21:31 ` Dave Chinner
2017-03-17 12:23 ` Goldwyn Rodrigues
2017-03-20 17:33 ` Jan Kara
2017-03-15 21:51 ` Goldwyn Rodrigues [this message]
2017-03-15 21:51 ` [PATCH 7/8] nowait aio: xfs Goldwyn Rodrigues
2017-03-15 21:51 ` [PATCH 8/8] nowait aio: btrfs Goldwyn Rodrigues
2017-04-03 18:52 [PATCH 0/8 v4] No wait AIO Goldwyn Rodrigues
2017-04-03 18:53 ` [PATCH 6/8] nowait aio: ext4 Goldwyn Rodrigues
2017-04-04 7:58 ` Jan Kara
2017-04-04 8:41 ` Christoph Hellwig
2017-04-04 18:41 ` Goldwyn Rodrigues
2017-04-10 7:45 ` Christoph Hellwig
[not found] ` <20170410074539.GA18250-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2017-04-10 12:37 ` Jan Kara
2017-04-10 14:39 ` Christoph Hellwig
2017-04-10 15:13 ` Jan Kara
2017-04-14 12:02 [PATCH 0/8 v6] No wait AIO Goldwyn Rodrigues
2017-04-14 12:02 ` [PATCH 6/8] nowait aio: ext4 Goldwyn Rodrigues
2017-05-09 12:22 [PATCH 0/8 v7] No wait AIO Goldwyn Rodrigues
2017-05-09 12:22 ` [PATCH 6/8] nowait aio: ext4 Goldwyn Rodrigues
[not found] ` <20170509122219.31756-7-rgoldwyn-l3A5Bk7waGM@public.gmane.org>
2017-05-09 14:57 ` Jan Kara
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