[8/8] nowait aio: btrfs

Submitted by Goldwyn Rodrigues on April 14, 2017, 12:02 p.m.

Details

Message ID 20170414120257.8932-9-rgoldwyn@suse.de
State New
Headers show

Commit Message

Goldwyn Rodrigues April 14, 2017, 12:02 p.m.
From: Goldwyn Rodrigues <rgoldwyn@suse.com>

Return EAGAIN if any of the following checks fail
 + i_rwsem is not lockable
 + NODATACOW or PREALLOC is not set
 + Cannot nocow at the desired location
 + Writing beyond end of file which is not allocated

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
---
 fs/btrfs/file.c  | 25 ++++++++++++++++++++-----
 fs/btrfs/inode.c |  3 +++
 2 files changed, 23 insertions(+), 5 deletions(-)

Comments

David Sterba April 18, 2017, 11:39 a.m.
On Fri, Apr 14, 2017 at 07:02:57AM -0500, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues <rgoldwyn@suse.com>
> 
> Return EAGAIN if any of the following checks fail
>  + i_rwsem is not lockable
>  + NODATACOW or PREALLOC is not set
>  + Cannot nocow at the desired location
>  + Writing beyond end of file which is not allocated
> 
> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>

Acked-by: David Sterba <dsterba@suse.com>

> +	if ((iocb->ki_flags & IOCB_NOWAIT) &&
> +			(iocb->ki_flags & IOCB_DIRECT)) {
> +		/* Don't sleep on inode rwsem */
> +		if (!inode_trylock(inode))
> +			return -EAGAIN;
> +		/*
> +		 * We will allocate space in case nodatacow is not set,
> +		 * so bail
> +		 */
> +		if (!(BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW |
> +					      BTRFS_INODE_PREALLOC)) ||
> +		    check_can_nocow(BTRFS_I(inode), pos, &count) <= 0) {
> +			inode_unlock(inode);
> +			return -EAGAIN;
> +		}
> +	} else

	} else {

> +		inode_lock(inode);

	}

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diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 520cb7230b2d..a870e5dd2b4d 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1823,12 +1823,29 @@  static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
 	ssize_t num_written = 0;
 	bool sync = (file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host);
 	ssize_t err;
-	loff_t pos;
-	size_t count;
+	loff_t pos = iocb->ki_pos;
+	size_t count = iov_iter_count(from);
 	loff_t oldsize;
 	int clean_page = 0;
 
-	inode_lock(inode);
+	if ((iocb->ki_flags & IOCB_NOWAIT) &&
+			(iocb->ki_flags & IOCB_DIRECT)) {
+		/* Don't sleep on inode rwsem */
+		if (!inode_trylock(inode))
+			return -EAGAIN;
+		/*
+		 * We will allocate space in case nodatacow is not set,
+		 * so bail
+		 */
+		if (!(BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW |
+					      BTRFS_INODE_PREALLOC)) ||
+		    check_can_nocow(BTRFS_I(inode), pos, &count) <= 0) {
+			inode_unlock(inode);
+			return -EAGAIN;
+		}
+	} else
+		inode_lock(inode);
+
 	err = generic_write_checks(iocb, from);
 	if (err <= 0) {
 		inode_unlock(inode);
@@ -1862,8 +1879,6 @@  static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
 	 */
 	update_time_for_write(inode);
 
-	pos = iocb->ki_pos;
-	count = iov_iter_count(from);
 	start_pos = round_down(pos, fs_info->sectorsize);
 	oldsize = i_size_read(inode);
 	if (start_pos > oldsize) {
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index a18510be76c1..d91b21a76d6d 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -8627,6 +8627,9 @@  static ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 			dio_data.overwrite = 1;
 			inode_unlock(inode);
 			relock = true;
+		} else if (iocb->ki_flags & IOCB_NOWAIT) {
+			ret = -EAGAIN;
+			goto out;
 		}
 		ret = btrfs_delalloc_reserve_space(inode, offset, count);
 		if (ret)