On 14.02.2017 04:46, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
>
> Return EAGAIN if any of the following checks fail
> + i_rwsem is lockable
> + NODATACOW or PREALLOC is set
perhaps you wanted to say "NODATACOW or PREALLOC is _not_ set"? See below
> + 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)) ||
The first part of the condition will evaluate to true only when both
btrfs_inode_nodatacow and btrfs_inodeprealloc are not set. The code
contradicts your statement in the change log.
> + 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)
>
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