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btrfs: nowait aio support 

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 <dsterba@suse.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Goldwyn Rodrigues 2017-06-20 07:05:49 -05:00 committed by Jens Axboe
parent 29a5d29ec1
commit edf064e7c6
2 changed files with 30 additions and 6 deletions
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33
fs/btrfs/file.c
View File

@ -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,

3
fs/btrfs/inode.c
View File

@ -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)