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xfs: move log iovec alignment to preparation function

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To include log op headers directly into the log iovec regions that
the ophdrs wrap, we need to move the buffer alignment code from
xlog_finish_iovec() to xlog_prepare_iovec(). This is because the
xlog_op_header is only 12 bytes long, and we need the buffer that
the caller formats their data into to be 8 byte aligned.

Hence once we start prepending the ophdr in xlog_prepare_iovec(), we
are going to need to manage the padding directly to ensure that the
buffer pointer returned is correctly aligned.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Chandan Babu R <chandan.babu@oracle.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This commit is contained in:
Dave Chinner 2022-04-21 10:34:49 +10:00 committed by Dave Chinner
parent c7610dceed
commit 3c352bef83
1 changed files with 14 additions and 11 deletions
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25
fs/xfs/xfs_log.h
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@ -21,6 +21,16 @@ struct xfs_log_vec {
#define XFS_LOG_VEC_ORDERED (-1)
/*
* We need to make sure the buffer pointer returned is naturally aligned for the
* biggest basic data type we put into it. We have already accounted for this
* padding when sizing the buffer.
*
* However, this padding does not get written into the log, and hence we have to
* track the space used by the log vectors separately to prevent log space hangs
* due to inaccurate accounting (i.e. a leak) of the used log space through the
* CIL context ticket.
*/
static inline void *
xlog_prepare_iovec(struct xfs_log_vec *lv, struct xfs_log_iovec **vecp,
uint type)
@ -34,6 +44,9 @@ xlog_prepare_iovec(struct xfs_log_vec *lv, struct xfs_log_iovec **vecp,
vec = &lv->lv_iovecp[0];
}
if (!IS_ALIGNED(lv->lv_buf_len, sizeof(uint64_t)))
lv->lv_buf_len = round_up(lv->lv_buf_len, sizeof(uint64_t));
vec->i_type = type;
vec->i_addr = lv->lv_buf + lv->lv_buf_len;
@ -43,20 +56,10 @@ xlog_prepare_iovec(struct xfs_log_vec *lv, struct xfs_log_iovec **vecp,
return vec->i_addr;
}
/*
* We need to make sure the next buffer is naturally aligned for the biggest
* basic data type we put into it. We already accounted for this padding when
* sizing the buffer.
*
* However, this padding does not get written into the log, and hence we have to
* track the space used by the log vectors separately to prevent log space hangs
* due to inaccurate accounting (i.e. a leak) of the used log space through the
* CIL context ticket.
*/
static inline void
xlog_finish_iovec(struct xfs_log_vec *lv, struct xfs_log_iovec *vec, int len)
{
lv->lv_buf_len += round_up(len, sizeof(uint64_t));
lv->lv_buf_len += len;
lv->lv_bytes += len;
vec->i_len = len;
}