From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
Return EAGAIN if any of the following checks fail
+ i_rwsem is lockable
+ NODATACOW or PREALLOC is set
+ Can nocow at the desired location
+ Writing beyond end of file
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
---
fs/btrfs/file.c | 25 ++++++++++++++++++++-----
fs/btrfs/inode.c | 3 +++
2 files changed, 23 insertions(+), 5 deletions(-)
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 3a14c87..f4dcc7a 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1804,12 +1804,29 @@ 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_NONBLOCKING) &&
+ (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(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);
@@ -1843,8 +1860,6 @@ 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, root->sectorsize);
oldsize = i_size_read(inode);
if (start_pos > oldsize) {
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index be4da91..9911ebd 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -8690,6 +8690,9 @@ static ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
if (offset + count <= inode->i_size) {
inode_unlock(inode);
relock = true;
+ } else if (iocb->ki_flags & IOCB_NONBLOCKING) {
+ ret = -EAGAIN;
+ goto out;
}
ret = btrfs_delalloc_reserve_space(inode, offset, count);
if (ret)
--
2.10.2
