2016-11-01 21:06:19

by Jan Kara

[permalink] [raw]
Subject: [PATCH 09/11] ext4: Rip out DAX handling from direct IO path

Reads and writes for DAX inodes should no longer end up in direct IO
code. Rip out the support and add a warning.

Signed-off-by: Jan Kara <[email protected]>
---
fs/ext4/inode.c | 49 +++++++++++++++----------------------------------
1 file changed, 15 insertions(+), 34 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 001fef06ea97..e236b84fc079 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3571,19 +3571,7 @@ static ssize_t ext4_direct_IO_write(struct kiocb *iocb, struct iov_iter *iter)
iocb->private = NULL;
if (overwrite)
get_block_func = ext4_dio_get_block_overwrite;
- else if (IS_DAX(inode)) {
- /*
- * We can avoid zeroing for aligned DAX writes beyond EOF. Other
- * writes need zeroing either because they can race with page
- * faults or because they use partial blocks.
- */
- if (round_down(offset, 1<<inode->i_blkbits) >= inode->i_size &&
- ext4_aligned_io(inode, offset, count))
- get_block_func = ext4_dio_get_block;
- else
- get_block_func = ext4_dax_get_block;
- dio_flags = DIO_LOCKING;
- } else if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) ||
+ else if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) ||
round_down(offset, 1 << inode->i_blkbits) >= inode->i_size) {
get_block_func = ext4_dio_get_block;
dio_flags = DIO_LOCKING | DIO_SKIP_HOLES;
@@ -3597,14 +3585,9 @@ static ssize_t ext4_direct_IO_write(struct kiocb *iocb, struct iov_iter *iter)
#ifdef CONFIG_EXT4_FS_ENCRYPTION
BUG_ON(ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode));
#endif
- if (IS_DAX(inode)) {
- ret = dax_do_io(iocb, inode, iter, get_block_func,
- ext4_end_io_dio, dio_flags);
- } else
- ret = __blockdev_direct_IO(iocb, inode,
- inode->i_sb->s_bdev, iter,
- get_block_func,
- ext4_end_io_dio, NULL, dio_flags);
+ ret = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev, iter,
+ get_block_func, ext4_end_io_dio, NULL,
+ dio_flags);

if (ret > 0 && !overwrite && ext4_test_inode_state(inode,
EXT4_STATE_DIO_UNWRITTEN)) {
@@ -3673,6 +3656,7 @@ static ssize_t ext4_direct_IO_read(struct kiocb *iocb, struct iov_iter *iter)
{
struct address_space *mapping = iocb->ki_filp->f_mapping;
struct inode *inode = mapping->host;
+ size_t count = iov_iter_count(iter);
ssize_t ret;

/*
@@ -3681,19 +3665,12 @@ static ssize_t ext4_direct_IO_read(struct kiocb *iocb, struct iov_iter *iter)
* we are protected against page writeback as well.
*/
inode_lock_shared(inode);
- if (IS_DAX(inode)) {
- ret = dax_do_io(iocb, inode, iter, ext4_dio_get_block, NULL, 0);
- } else {
- size_t count = iov_iter_count(iter);
-
- ret = filemap_write_and_wait_range(mapping, iocb->ki_pos,
- iocb->ki_pos + count);
- if (ret)
- goto out_unlock;
- ret = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev,
- iter, ext4_dio_get_block,
- NULL, NULL, 0);
- }
+ ret = filemap_write_and_wait_range(mapping, iocb->ki_pos,
+ iocb->ki_pos + count);
+ if (ret)
+ goto out_unlock;
+ ret = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev,
+ iter, ext4_dio_get_block, NULL, NULL, 0);
out_unlock:
inode_unlock_shared(inode);
return ret;
@@ -3722,6 +3699,10 @@ static ssize_t ext4_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
if (ext4_has_inline_data(inode))
return 0;

+ /* DAX uses iomap path now */
+ if (WARN_ON_ONCE(IS_DAX(inode)))
+ return 0;
+
trace_ext4_direct_IO_enter(inode, offset, count, iov_iter_rw(iter));
if (iov_iter_rw(iter) == READ)
ret = ext4_direct_IO_read(iocb, iter);
--
2.6.6