From: Goldwyn Rodrigues <rgold...@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
Acked-by: David Sterba <dste...@suse.com>
Signed-off-by: Goldwyn Rodrigues <rgold...@suse.com>
---
fs/btrfs/file.c | 33 +++++++++++++++++++++++++++------
fs/btrfs/inode.c | 3 +++
2 files changed, 30 insertions(+), 6 deletions(-)
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index da1096eb1a40..59e2dccdf75b 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1875,12 +1875,29 @@ 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);
@@ -1914,8 +1931,6 @@ 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) {
@@ -3071,13 +3086,19 @@ static loff_t btrfs_file_llseek(struct file *file,
loff_t offset, int whence)
return offset;
}
+static int btrfs_file_open(struct inode *inode, struct file *filp)
+{
+ filp->f_mode |= FMODE_AIO_NOWAIT;
+ return generic_file_open(inode, filp);
+}
+
const struct file_operations btrfs_file_operations = {
.llseek = btrfs_file_llseek,
.read_iter = generic_file_read_iter,
.splice_read = generic_file_splice_read,
.write_iter = btrfs_file_write_iter,
.mmap = btrfs_file_mmap,
- .open = generic_file_open,
+ .open = btrfs_file_open,
.release = btrfs_release_file,
.fsync = btrfs_sync_file,
.fallocate = btrfs_fallocate,
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index f942293dd7e7..556c93060606 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -8754,6 +8754,9 @@ 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)
--
2.12.0
