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SubjectRe: [PATCH] f2fs: add nowait aio support
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On 2018/3/2 15:48, Hyunchul Lee wrote:
> From: Hyunchul Lee <cheol.lee@lge.com>
>
> This patch adds nowait aio support[1].
>
> Return EAGAIN if any of the following checks fail for direct I/O:
> - i_rwsem is not lockable
> - Blocks are not allocated at the write location
>
> And xfstests generic/471 is passed.
>
> [1]: 6be96d "Introduce RWF_NOWAIT and FMODE_AIO_NOWAIT"
>
> Signed-off-by: Hyunchul Lee <cheol.lee@lge.com>
> ---
> fs/f2fs/data.c | 36 +++++++++++++++++++++++++++---------
> fs/f2fs/f2fs.h | 8 ++++++++
> fs/f2fs/file.c | 35 +++++++++++++++++++++++++++++------
> 3 files changed, 64 insertions(+), 15 deletions(-)
>
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 6c3c978..9a550c5 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -839,13 +839,6 @@ static int __allocate_data_block(struct dnode_of_data *dn, int seg_type)
> return 0;
> }
>
> -static inline bool __force_buffered_io(struct inode *inode, int rw)
> -{
> - return (f2fs_encrypted_file(inode) ||
> - (rw == WRITE && test_opt(F2FS_I_SB(inode), LFS)) ||
> - F2FS_I_SB(inode)->s_ndevs);
> -}
> -
> int f2fs_preallocate_blocks(struct kiocb *iocb, struct iov_iter *from)
> {
> struct inode *inode = file_inode(iocb->ki_filp);
> @@ -877,7 +870,7 @@ int f2fs_preallocate_blocks(struct kiocb *iocb, struct iov_iter *from)
>
> if (direct_io) {
> map.m_seg_type = rw_hint_to_seg_type(iocb->ki_hint);
> - flag = __force_buffered_io(inode, WRITE) ?
> + flag = f2fs_force_buffered_io(inode, WRITE) ?
> F2FS_GET_BLOCK_PRE_AIO :
> F2FS_GET_BLOCK_PRE_DIO;
> goto map_blocks;
> @@ -1121,6 +1114,31 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
> return err;
> }
>
> +bool f2fs_overwrite_io(struct inode *inode, loff_t pos, size_t len)
> +{
> + struct f2fs_map_blocks map;
> + block_t last_lblk;
> + int err;
> +
> + if (pos + len > i_size_read(inode))
> + return false;
> +
> + map.m_lblk = F2FS_BYTES_TO_BLK(pos);
> + map.m_next_pgofs = 0;
> + map.m_next_extent = NULL;
> + map.m_seg_type = NO_CHECK_TYPE;
> + last_lblk = F2FS_BYTES_TO_BLK(pos + len) + 1;
> +
> + while (map.m_lblk < last_lblk) {
> + map.m_len = last_lblk - map.m_lblk;
> + err = f2fs_map_blocks(inode, &map, 0, 0);
> + if (err || map.m_len == 0)
> + return false;
> + map.m_lblk += map.m_len;
> + }
> + return true;
> +}
> +
> static int __get_data_block(struct inode *inode, sector_t iblock,
> struct buffer_head *bh, int create, int flag,
> pgoff_t *next_pgofs, int seg_type)
> @@ -2306,7 +2324,7 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
> if (err)
> return err;
>
> - if (__force_buffered_io(inode, rw))
> + if (f2fs_force_buffered_io(inode, rw))
> return 0;
>
> trace_f2fs_direct_IO_enter(inode, offset, count, rw);
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index f6dc706..351226e 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -2875,6 +2875,7 @@ void f2fs_invalidate_page(struct page *page, unsigned int offset,
> int f2fs_migrate_page(struct address_space *mapping, struct page *newpage,
> struct page *page, enum migrate_mode mode);
> #endif
> +bool f2fs_overwrite_io(struct inode *inode, loff_t pos, size_t len);
>
> /*
> * gc.c
> @@ -3259,4 +3260,11 @@ static inline bool f2fs_may_encrypt(struct inode *inode)
> #endif
> }
>
> +static inline bool f2fs_force_buffered_io(struct inode *inode, int rw)
> +{
> + return (f2fs_encrypted_file(inode) ||
> + (rw == WRITE && test_opt(F2FS_I_SB(inode), LFS)) ||
> + F2FS_I_SB(inode)->s_ndevs);
> +}
> +
> #endif
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 6a202e5..1051edd 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -479,6 +479,9 @@ static int f2fs_file_open(struct inode *inode, struct file *filp)
>
> if (err)
> return err;
> +
> + filp->f_mode |= FMODE_NOWAIT;
> +
> return dquot_file_open(inode, filp);
> }
>
> @@ -2895,7 +2898,15 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
> if (unlikely(f2fs_cp_error(F2FS_I_SB(inode))))
> return -EIO;
>
> - inode_lock(inode);
> + if ((iocb->ki_flags & IOCB_NOWAIT) && !(iocb->ki_flags & IOCB_DIRECT))
> + return -EINVAL;

EOPNOTSUPP to keep line with ext4?

> +
> + if (!inode_trylock(inode)) {
> + if (iocb->ki_flags & IOCB_NOWAIT)
> + return -EAGAIN;
> + inode_lock(inode);
> + }
> +
> ret = generic_write_checks(iocb, from);
> if (ret > 0) {
> int err;
> @@ -2903,11 +2914,23 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
> if (iov_iter_fault_in_readable(from, iov_iter_count(from)))
> set_inode_flag(inode, FI_NO_PREALLOC);
>
> - err = f2fs_preallocate_blocks(iocb, from);
> - if (err) {
> - clear_inode_flag(inode, FI_NO_PREALLOC);
> - inode_unlock(inode);
> - return err;
> + if ((iocb->ki_flags & IOCB_NOWAIT) &&
> + (iocb->ki_flags & IOCB_DIRECT)) {
> + if (!f2fs_overwrite_io(inode, iocb->ki_pos,
> + iov_iter_count(from)) ||
> + f2fs_has_inline_data(inode) ||
> + f2fs_force_buffered_io(inode, WRITE)) {
> + inode_unlock(inode);
> + return -EAGAIN;
> + }
> +
> + } else {
> + err = f2fs_preallocate_blocks(iocb, from);
> + if (err) {
> + clear_inode_flag(inode, FI_NO_PREALLOC);
> + inode_unlock(inode);
> + return err;
> + }

Do we need to change down_read to down_read_trylock in f2fs_direct_IO when we
use 'nowait' mode of aio?

Thanks,

> }
> blk_start_plug(&plug);
> ret = __generic_file_write_iter(iocb, from);
>

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