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Subject[PATCH v2] f2fs: add nowait aio support
Date
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>
---
Changes from v1:
- Return EGAIN if dio_rwsem is not lockable in f2fs_direct_IO
- Fix the wrong calculation of last_lblk in f2fs_overwrite_io

fs/f2fs/data.c | 47 +++++++++++++++++++++++++++++++++++++----------
fs/f2fs/f2fs.h | 8 ++++++++
fs/f2fs/file.c | 35 +++++++++++++++++++++++++++++------
3 files changed, 74 insertions(+), 16 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 6c3c978..b27ea1e 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) + 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);
@@ -2314,7 +2332,15 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
if (rw == WRITE && whint_mode == WHINT_MODE_OFF)
iocb->ki_hint = WRITE_LIFE_NOT_SET;

- down_read(&F2FS_I(inode)->dio_rwsem[rw]);
+ if (!down_read_trylock(&F2FS_I(inode)->dio_rwsem[rw])) {
+ if (iocb->ki_flags & IOCB_NOWAIT) {
+ iocb->ki_hint = hint;
+ err = -EAGAIN;
+ goto out;
+ }
+ down_read(&F2FS_I(inode)->dio_rwsem[rw]);
+ }
+
err = blockdev_direct_IO(iocb, inode, iter, get_data_block_dio);
up_read(&F2FS_I(inode)->dio_rwsem[rw]);

@@ -2330,6 +2356,7 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
}
}

+out:
trace_f2fs_direct_IO_exit(inode, offset, count, rw, err);

return err;
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;
+
+ 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;
+ }
}
blk_start_plug(&plug);
ret = __generic_file_write_iter(iocb, from);
--
1.9.1
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