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xfs: don't allocate an ioend for direct I/O completions
Back in the days when the direct I/O ->end_io callback could be called from interrupt context for AIO we needed a structure to hand off to the workqueue, and reused the ioend structure for this purpose. These days ->end_io is always called from user or workqueue context, which allows us to avoid this memory allocation and simplify the code significantly. [dchinner: removed now unused xfs_finish_ioend_sync() function after Brian Foster did an initial review. ] Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
This commit is contained in:
Christoph Hellwig
Dave Chinner
parent
f3d215526e
commit
2ba6623702
@ -135,30 +135,22 @@ xfs_setfilesize_trans_alloc(
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*/
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STATIC int
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xfs_setfilesize(
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struct xfs_ioend *ioend)
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struct xfs_inode *ip,
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struct xfs_trans *tp,
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xfs_off_t offset,
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size_t size)
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{
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struct xfs_inode *ip = XFS_I(ioend->io_inode);
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struct xfs_trans *tp = ioend->io_append_trans;
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xfs_fsize_t isize;
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/*
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* The transaction may have been allocated in the I/O submission thread,
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* thus we need to mark ourselves as beeing in a transaction manually.
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* Similarly for freeze protection.
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*/
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current_set_flags_nested(&tp->t_pflags, PF_FSTRANS);
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rwsem_acquire_read(&VFS_I(ip)->i_sb->s_writers.lock_map[SB_FREEZE_FS-1],
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0, 1, _THIS_IP_);
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xfs_ilock(ip, XFS_ILOCK_EXCL);
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isize = xfs_new_eof(ip, ioend->io_offset + ioend->io_size);
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isize = xfs_new_eof(ip, offset + size);
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if (!isize) {
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xfs_iunlock(ip, XFS_ILOCK_EXCL);
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xfs_trans_cancel(tp, 0);
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return 0;
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}
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trace_xfs_setfilesize(ip, ioend->io_offset, ioend->io_size);
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trace_xfs_setfilesize(ip, offset, size);
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ip->i_d.di_size = isize;
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xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
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@ -167,6 +159,25 @@ xfs_setfilesize(
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return xfs_trans_commit(tp, 0);
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}
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STATIC int
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xfs_setfilesize_ioend(
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struct xfs_ioend *ioend)
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{
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struct xfs_inode *ip = XFS_I(ioend->io_inode);
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struct xfs_trans *tp = ioend->io_append_trans;
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/*
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* The transaction may have been allocated in the I/O submission thread,
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* thus we need to mark ourselves as being in a transaction manually.
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* Similarly for freeze protection.
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*/
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current_set_flags_nested(&tp->t_pflags, PF_FSTRANS);
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rwsem_acquire_read(&VFS_I(ip)->i_sb->s_writers.lock_map[SB_FREEZE_FS-1],
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0, 1, _THIS_IP_);
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return xfs_setfilesize(ip, tp, ioend->io_offset, ioend->io_size);
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}
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/*
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* Schedule IO completion handling on the final put of an ioend.
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*
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@ -182,8 +193,7 @@ xfs_finish_ioend(
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if (ioend->io_type == XFS_IO_UNWRITTEN)
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queue_work(mp->m_unwritten_workqueue, &ioend->io_work);
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else if (ioend->io_append_trans ||
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(ioend->io_isdirect && xfs_ioend_is_append(ioend)))
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else if (ioend->io_append_trans)
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queue_work(mp->m_data_workqueue, &ioend->io_work);
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else
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xfs_destroy_ioend(ioend);
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@ -215,22 +225,8 @@ xfs_end_io(
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if (ioend->io_type == XFS_IO_UNWRITTEN) {
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error = xfs_iomap_write_unwritten(ip, ioend->io_offset,
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ioend->io_size);
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} else if (ioend->io_isdirect && xfs_ioend_is_append(ioend)) {
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/*
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* For direct I/O we do not know if we need to allocate blocks
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* or not so we can't preallocate an append transaction as that
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* results in nested reservations and log space deadlocks. Hence
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* allocate the transaction here. While this is sub-optimal and
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* can block IO completion for some time, we're stuck with doing
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* it this way until we can pass the ioend to the direct IO
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* allocation callbacks and avoid nesting that way.
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*/
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error = xfs_setfilesize_trans_alloc(ioend);
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if (error)
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goto done;
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error = xfs_setfilesize(ioend);
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} else if (ioend->io_append_trans) {
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error = xfs_setfilesize(ioend);
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error = xfs_setfilesize_ioend(ioend);
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} else {
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ASSERT(!xfs_ioend_is_append(ioend));
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}
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@ -241,17 +237,6 @@ done:
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xfs_destroy_ioend(ioend);
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}
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/*
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* Call IO completion handling in caller context on the final put of an ioend.
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*/
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STATIC void
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xfs_finish_ioend_sync(
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struct xfs_ioend *ioend)
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{
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if (atomic_dec_and_test(&ioend->io_remaining))
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xfs_end_io(&ioend->io_work);
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}
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/*
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* Allocate and initialise an IO completion structure.
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* We need to track unwritten extent write completion here initially.
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@ -273,7 +258,6 @@ xfs_alloc_ioend(
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* all the I/O from calling the completion routine too early.
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*/
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atomic_set(&ioend->io_remaining, 1);
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ioend->io_isdirect = 0;
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ioend->io_error = 0;
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ioend->io_list = NULL;
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ioend->io_type = type;
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@ -1459,11 +1443,7 @@ xfs_get_blocks_direct(
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*
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* If the private argument is non-NULL __xfs_get_blocks signals us that we
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* need to issue a transaction to convert the range from unwritten to written
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* extents. In case this is regular synchronous I/O we just call xfs_end_io
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* to do this and we are done. But in case this was a successful AIO
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* request this handler is called from interrupt context, from which we
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* can't start transactions. In that case offload the I/O completion to
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* the workqueues we also use for buffered I/O completion.
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* extents.
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*/
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STATIC void
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xfs_end_io_direct_write(
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@ -1472,7 +1452,12 @@ xfs_end_io_direct_write(
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ssize_t size,
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void *private)
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{
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struct xfs_ioend *ioend = iocb->private;
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struct inode *inode = file_inode(iocb->ki_filp);
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struct xfs_inode *ip = XFS_I(inode);
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struct xfs_mount *mp = ip->i_mount;
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if (XFS_FORCED_SHUTDOWN(mp))
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return;
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/*
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* While the generic direct I/O code updates the inode size, it does
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@ -1480,22 +1465,33 @@ xfs_end_io_direct_write(
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* end_io handler thinks the on-disk size is outside the in-core
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* size. To prevent this just update it a little bit earlier here.
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*/
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if (offset + size > i_size_read(ioend->io_inode))
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i_size_write(ioend->io_inode, offset + size);
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if (offset + size > i_size_read(inode))
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i_size_write(inode, offset + size);
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/*
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* blockdev_direct_IO can return an error even after the I/O
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* completion handler was called. Thus we need to protect
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* against double-freeing.
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* For direct I/O we do not know if we need to allocate blocks or not,
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* so we can't preallocate an append transaction, as that results in
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* nested reservations and log space deadlocks. Hence allocate the
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* transaction here. While this is sub-optimal and can block IO
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* completion for some time, we're stuck with doing it this way until
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* we can pass the ioend to the direct IO allocation callbacks and
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* avoid nesting that way.
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*/
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iocb->private = NULL;
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if (private && size > 0) {
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xfs_iomap_write_unwritten(ip, offset, size);
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} else if (offset + size > ip->i_d.di_size) {
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struct xfs_trans *tp;
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int error;
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ioend->io_offset = offset;
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ioend->io_size = size;
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if (private && size > 0)
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ioend->io_type = XFS_IO_UNWRITTEN;
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tp = xfs_trans_alloc(mp, XFS_TRANS_FSYNC_TS);
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error = xfs_trans_reserve(tp, &M_RES(mp)->tr_fsyncts, 0, 0);
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if (error) {
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xfs_trans_cancel(tp, 0);
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return;
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}
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xfs_finish_ioend_sync(ioend);
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xfs_setfilesize(ip, tp, offset, size);
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}
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}
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STATIC ssize_t
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@ -1507,39 +1503,16 @@ xfs_vm_direct_IO(
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{
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struct inode *inode = iocb->ki_filp->f_mapping->host;
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struct block_device *bdev = xfs_find_bdev_for_inode(inode);
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struct xfs_ioend *ioend = NULL;
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ssize_t ret;
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if (rw & WRITE) {
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size_t size = iov_iter_count(iter);
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/*
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* We cannot preallocate a size update transaction here as we
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* don't know whether allocation is necessary or not. Hence we
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* can only tell IO completion that one is necessary if we are
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* not doing unwritten extent conversion.
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*/
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iocb->private = ioend = xfs_alloc_ioend(inode, XFS_IO_DIRECT);
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if (offset + size > XFS_I(inode)->i_d.di_size)
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ioend->io_isdirect = 1;
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ret = __blockdev_direct_IO(rw, iocb, inode, bdev, iter,
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return __blockdev_direct_IO(rw, iocb, inode, bdev, iter,
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offset, xfs_get_blocks_direct,
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xfs_end_io_direct_write, NULL,
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DIO_ASYNC_EXTEND);
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if (ret != -EIOCBQUEUED && iocb->private)
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goto out_destroy_ioend;
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} else {
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ret = __blockdev_direct_IO(rw, iocb, inode, bdev, iter,
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offset, xfs_get_blocks_direct,
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NULL, NULL, 0);
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}
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return ret;
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out_destroy_ioend:
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xfs_destroy_ioend(ioend);
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return ret;
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return __blockdev_direct_IO(rw, iocb, inode, bdev, iter,
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offset, xfs_get_blocks_direct,
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NULL, NULL, 0);
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}
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/*
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@ -24,14 +24,12 @@ extern mempool_t *xfs_ioend_pool;
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* Types of I/O for bmap clustering and I/O completion tracking.
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*/
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enum {
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XFS_IO_DIRECT = 0, /* special case for direct I/O ioends */
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XFS_IO_DELALLOC, /* covers delalloc region */
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XFS_IO_UNWRITTEN, /* covers allocated but uninitialized data */
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XFS_IO_OVERWRITE, /* covers already allocated extent */
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};
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#define XFS_IO_TYPES \
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{ 0, "" }, \
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{ XFS_IO_DELALLOC, "delalloc" }, \
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{ XFS_IO_UNWRITTEN, "unwritten" }, \
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{ XFS_IO_OVERWRITE, "overwrite" }
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@ -45,7 +43,6 @@ typedef struct xfs_ioend {
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unsigned int io_type; /* delalloc / unwritten */
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int io_error; /* I/O error code */
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atomic_t io_remaining; /* hold count */
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unsigned int io_isdirect : 1;/* direct I/O */
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struct inode *io_inode; /* file being written to */
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struct buffer_head *io_buffer_head;/* buffer linked list head */
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struct buffer_head *io_buffer_tail;/* buffer linked list tail */
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