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xfs: refactor buffer submission into a common helper

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Sync and async buffer submission both do generally similar things
with a couple odd exceptions. Refactor the core buffer submission
code into a common helper to isolate buffer submission from
completion handling of synchronous buffer I/O.

This patch does not change behavior. It is a step towards support
for using synchronous buffer I/O via synchronous delwri queue
submission.

Designed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This commit is contained in:
Brian Foster 2018-07-11 22:26:34 -07:00 committed by Darrick J. Wong
parent 5fdd97944e
commit eaebb515f1
2 changed files with 45 additions and 57 deletions
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101
fs/xfs/xfs_buf.c
View file

@ -1458,22 +1458,20 @@ _xfs_buf_ioapply(
* a call to this function unless the caller holds an additional reference
* itself.
*/
void
xfs_buf_submit(
static int
__xfs_buf_submit(
struct xfs_buf *bp)
{
trace_xfs_buf_submit(bp, _RET_IP_);
ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
ASSERT(bp->b_flags & XBF_ASYNC);
/* on shutdown we stale and complete the buffer immediately */
if (XFS_FORCED_SHUTDOWN(bp->b_target->bt_mount)) {
xfs_buf_ioerror(bp, -EIO);
bp->b_flags &= ~XBF_DONE;
xfs_buf_stale(bp);
xfs_buf_ioend(bp);
return;
return -EIO;
}
if (bp->b_flags & XBF_WRITE)
@ -1482,6 +1480,39 @@ xfs_buf_submit(
/* clear the internal error state to avoid spurious errors */
bp->b_io_error = 0;
/*
* Set the count to 1 initially, this will stop an I/O completion
* callout which happens before we have started all the I/O from calling
* xfs_buf_ioend too early.
*/
atomic_set(&bp->b_io_remaining, 1);
if (bp->b_flags & XBF_ASYNC)
xfs_buf_ioacct_inc(bp);
_xfs_buf_ioapply(bp);
/*
* If _xfs_buf_ioapply failed, we can get back here with only the IO
* reference we took above. If we drop it to zero, run completion so
* that we don't return to the caller with completion still pending.
*/
if (atomic_dec_and_test(&bp->b_io_remaining) == 1) {
if (bp->b_error || !(bp->b_flags & XBF_ASYNC))
xfs_buf_ioend(bp);
else
xfs_buf_ioend_async(bp);
}
return 0;
}
void
xfs_buf_submit(
struct xfs_buf *bp)
{
int error;
ASSERT(bp->b_flags & XBF_ASYNC);
/*
* The caller's reference is released during I/O completion.
* This occurs some time after the last b_io_remaining reference is
@ -1492,29 +1523,12 @@ xfs_buf_submit(
*/
xfs_buf_hold(bp);
/*
* Set the count to 1 initially, this will stop an I/O completion
* callout which happens before we have started all the I/O from calling
* xfs_buf_ioend too early.
*/
atomic_set(&bp->b_io_remaining, 1);
xfs_buf_ioacct_inc(bp);
_xfs_buf_ioapply(bp);
error = __xfs_buf_submit(bp);
if (error)
xfs_buf_ioend(bp);
/*
* If _xfs_buf_ioapply failed, we can get back here with only the IO
* reference we took above. If we drop it to zero, run completion so
* that we don't return to the caller with completion still pending.
*/
if (atomic_dec_and_test(&bp->b_io_remaining) == 1) {
if (bp->b_error)
xfs_buf_ioend(bp);
else
xfs_buf_ioend_async(bp);
}
xfs_buf_rele(bp);
/* Note: it is not safe to reference bp now we've dropped our ref */
xfs_buf_rele(bp);
}
/*
@ -1526,22 +1540,7 @@ xfs_buf_submit_wait(
{
int error;
trace_xfs_buf_submit_wait(bp, _RET_IP_);
ASSERT(!(bp->b_flags & (_XBF_DELWRI_Q | XBF_ASYNC)));
if (XFS_FORCED_SHUTDOWN(bp->b_target->bt_mount)) {
xfs_buf_ioerror(bp, -EIO);
xfs_buf_stale(bp);
bp->b_flags &= ~XBF_DONE;
return -EIO;
}
if (bp->b_flags & XBF_WRITE)
xfs_buf_wait_unpin(bp);
/* clear the internal error state to avoid spurious errors */
bp->b_io_error = 0;
ASSERT(!(bp->b_flags & XBF_ASYNC));
/*
* For synchronous IO, the IO does not inherit the submitters reference
@ -1551,20 +1550,9 @@ xfs_buf_submit_wait(
*/
xfs_buf_hold(bp);
/*
* Set the count to 1 initially, this will stop an I/O completion
* callout which happens before we have started all the I/O from calling
* xfs_buf_ioend too early.
*/
atomic_set(&bp->b_io_remaining, 1);
_xfs_buf_ioapply(bp);
/*
* make sure we run completion synchronously if it raced with us and is
* already complete.
*/
if (atomic_dec_and_test(&bp->b_io_remaining) == 1)
xfs_buf_ioend(bp);
error = __xfs_buf_submit(bp);
if (error)
goto out;
/* wait for completion before gathering the error from the buffer */
trace_xfs_buf_iowait(bp, _RET_IP_);
@ -1572,6 +1560,7 @@ xfs_buf_submit_wait(
trace_xfs_buf_iowait_done(bp, _RET_IP_);
error = bp->b_error;
out:
/*
* all done now, we can release the hold that keeps the buffer
* referenced for the entire IO.

1
fs/xfs/xfs_trace.h
View file

@ -310,7 +310,6 @@ DEFINE_BUF_EVENT(xfs_buf_hold);
DEFINE_BUF_EVENT(xfs_buf_rele);
DEFINE_BUF_EVENT(xfs_buf_iodone);
DEFINE_BUF_EVENT(xfs_buf_submit);
DEFINE_BUF_EVENT(xfs_buf_submit_wait);
DEFINE_BUF_EVENT(xfs_buf_lock);
DEFINE_BUF_EVENT(xfs_buf_lock_done);
DEFINE_BUF_EVENT(xfs_buf_trylock_fail);