On Thu, Aug 19, 2021 at 10:00:55AM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
>
> To stop external users from using b_bn as the disk address of the
> buffer, rename it to b_rhash_key to indicate that it is the buffer
> cache index, not the block number of the buffer. Code that needs the
> disk address should use xfs_buf_daddr() to obtain it.
>
> Do the rename and clean up any of the remaining internal b_bn users.
> Also clean up any remaining b_bn cruft that is now unused.
>
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Haaaa my brain didn't fall out!
Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
--D
> ---
> fs/xfs/xfs_buf.c | 19 +++++++++++--------
> fs/xfs/xfs_buf.h | 18 +-----------------
> 2 files changed, 12 insertions(+), 25 deletions(-)
>
> diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
> index c1bb6e41595b..047bd6e3f389 100644
> --- a/fs/xfs/xfs_buf.c
> +++ b/fs/xfs/xfs_buf.c
> @@ -251,7 +251,7 @@ _xfs_buf_alloc(
> return error;
> }
>
> - bp->b_bn = map[0].bm_bn;
> + bp->b_rhash_key = map[0].bm_bn;
> bp->b_length = 0;
> for (i = 0; i < nmaps; i++) {
> bp->b_maps[i].bm_bn = map[i].bm_bn;
> @@ -459,7 +459,7 @@ _xfs_buf_obj_cmp(
> */
> BUILD_BUG_ON(offsetof(struct xfs_buf_map, bm_bn) != 0);
>
> - if (bp->b_bn != map->bm_bn)
> + if (bp->b_rhash_key != map->bm_bn)
> return 1;
>
> if (unlikely(bp->b_length != map->bm_len)) {
> @@ -481,7 +481,7 @@ static const struct rhashtable_params xfs_buf_hash_params = {
> .min_size = 32, /* empty AGs have minimal footprint */
> .nelem_hint = 16,
> .key_len = sizeof(xfs_daddr_t),
> - .key_offset = offsetof(struct xfs_buf, b_bn),
> + .key_offset = offsetof(struct xfs_buf, b_rhash_key),
> .head_offset = offsetof(struct xfs_buf, b_rhash_head),
> .automatic_shrinking = true,
> .obj_cmpfn = _xfs_buf_obj_cmp,
> @@ -853,7 +853,9 @@ xfs_buf_readahead_map(
>
> /*
> * Read an uncached buffer from disk. Allocates and returns a locked
> - * buffer containing the disk contents or nothing.
> + * buffer containing the disk contents or nothing. Uncached buffers always have
> + * a cache index of XFS_BUF_DADDR_NULL so we can easily determine if the buffer
> + * is cached or uncached during fault diagnosis.
> */
> int
> xfs_buf_read_uncached(
> @@ -875,7 +877,7 @@ xfs_buf_read_uncached(
>
> /* set up the buffer for a read IO */
> ASSERT(bp->b_map_count == 1);
> - bp->b_bn = XFS_BUF_DADDR_NULL; /* always null for uncached buffers */
> + bp->b_rhash_key = XFS_BUF_DADDR_NULL;
> bp->b_maps[0].bm_bn = daddr;
> bp->b_flags |= XBF_READ;
> bp->b_ops = ops;
> @@ -1513,7 +1515,7 @@ _xfs_buf_ioapply(
> SHUTDOWN_CORRUPT_INCORE);
> return;
> }
> - } else if (bp->b_bn != XFS_BUF_DADDR_NULL) {
> + } else if (bp->b_rhash_key != XFS_BUF_DADDR_NULL) {
> struct xfs_mount *mp = bp->b_mount;
>
> /*
> @@ -1523,7 +1525,8 @@ _xfs_buf_ioapply(
> if (xfs_has_crc(mp)) {
> xfs_warn(mp,
> "%s: no buf ops on daddr 0x%llx len %d",
> - __func__, bp->b_bn, bp->b_length);
> + __func__, xfs_buf_daddr(bp),
> + bp->b_length);
> xfs_hex_dump(bp->b_addr,
> XFS_CORRUPTION_DUMP_LEN);
> dump_stack();
> @@ -1793,7 +1796,7 @@ xfs_buftarg_drain(
> xfs_buf_alert_ratelimited(bp,
> "XFS: Corruption Alert",
> "Corruption Alert: Buffer at daddr 0x%llx had permanent write failures!",
> - (long long)bp->b_bn);
> + (long long)xfs_buf_daddr(bp));
> }
> xfs_buf_rele(bp);
> }
> diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
> index 6db2fba44b46..6b0200b8007d 100644
> --- a/fs/xfs/xfs_buf.h
> +++ b/fs/xfs/xfs_buf.h
> @@ -134,11 +134,7 @@ struct xfs_buf {
> */
> struct rhash_head b_rhash_head; /* pag buffer hash node */
>
> - /*
> - * b_bn is the cache index. Do not use directly, use b_maps[0].bm_bn
> - * for the buffer disk address instead.
> - */
> - xfs_daddr_t b_bn;
> + xfs_daddr_t b_rhash_key; /* buffer cache index */
> int b_length; /* size of buffer in BBs */
> atomic_t b_hold; /* reference count */
> atomic_t b_lru_ref; /* lru reclaim ref count */
> @@ -301,18 +297,6 @@ extern int xfs_buf_delwri_pushbuf(struct xfs_buf *, struct list_head *);
> extern int xfs_buf_init(void);
> extern void xfs_buf_terminate(void);
>
> -/*
> - * These macros use the IO block map rather than b_bn. b_bn is now really
> - * just for the buffer cache index for cached buffers. As IO does not use b_bn
> - * anymore, uncached buffers do not use b_bn at all and hence must modify the IO
> - * map directly. Uncached buffers are not allowed to be discontiguous, so this
> - * is safe to do.
> - *
> - * In future, uncached buffers will pass the block number directly to the io
> - * request function and hence these macros will go away at that point.
> - */
> -#define XFS_BUF_SET_ADDR(bp, bno) ((bp)->b_maps[0].bm_bn = (xfs_daddr_t)(bno))
> -
> static inline xfs_daddr_t xfs_buf_daddr(struct xfs_buf *bp)
> {
> return bp->b_maps[0].bm_bn;
> --
> 2.31.1
>
