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[PATCH 4/9] xfs: add discontiguous buffer support to transactions

To: xfs@xxxxxxxxxxx
Subject: [PATCH 4/9] xfs: add discontiguous buffer support to transactions
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Fri, 8 Jun 2012 15:38:29 +1000
In-reply-to: <1339133914-11148-1-git-send-email-david@xxxxxxxxxxxxx>
References: <1339133914-11148-1-git-send-email-david@xxxxxxxxxxxxx>
From: Dave Chinner <dchinner@xxxxxxxxxx>

Now that the buffer cache supports discontiguous buffers, add
support to the transaction buffer interface for getting and reading
buffers.

Note that this patch does not convert the buffer item logging to
support discontiguous buffers. That will be done as a separate
commit.

Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
---
 fs/xfs/xfs_trans.h     |   50 +++++++++++++++++++++++++++++++----
 fs/xfs/xfs_trans_buf.c |   68 ++++++++++++++++++++++++------------------------
 2 files changed, 79 insertions(+), 39 deletions(-)

diff --git a/fs/xfs/xfs_trans.h b/fs/xfs/xfs_trans.h
index 7c37b53..bc2afd5 100644
--- a/fs/xfs/xfs_trans.h
+++ b/fs/xfs/xfs_trans.h
@@ -448,11 +448,51 @@ xfs_trans_t       *xfs_trans_dup(xfs_trans_t *);
 int            xfs_trans_reserve(xfs_trans_t *, uint, uint, uint,
                                  uint, uint);
 void           xfs_trans_mod_sb(xfs_trans_t *, uint, int64_t);
-struct xfs_buf *xfs_trans_get_buf(xfs_trans_t *, struct xfs_buftarg *, 
xfs_daddr_t,
-                                  int, uint);
-int            xfs_trans_read_buf(struct xfs_mount *, xfs_trans_t *,
-                                  struct xfs_buftarg *, xfs_daddr_t, int, uint,
-                                  struct xfs_buf **);
+
+struct xfs_buf *xfs_trans_get_buf_map(struct xfs_trans *tp,
+                                      struct xfs_buftarg *target,
+                                      struct xfs_buf_map *map, int nmaps,
+                                      uint flags);
+
+static inline struct xfs_buf *
+xfs_trans_get_buf(
+       struct xfs_trans        *tp,
+       struct xfs_buftarg      *target,
+       xfs_daddr_t             blkno,
+       int                     numblks,
+       uint                    flags)
+{
+       struct xfs_buf_map      map = {
+               .bm_bn = blkno,
+               .bm_len = numblks,
+       };
+       return xfs_trans_get_buf_map(tp, target, &map, 1, flags);
+}
+
+int            xfs_trans_read_buf_map(struct xfs_mount *mp,
+                                      struct xfs_trans *tp,
+                                      struct xfs_buftarg *target,
+                                      struct xfs_buf_map *map, int nmaps,
+                                      xfs_buf_flags_t flags,
+                                      struct xfs_buf **bpp);
+
+static inline int
+xfs_trans_read_buf(
+       struct xfs_mount        *mp,
+       struct xfs_trans        *tp,
+       struct xfs_buftarg      *target,
+       xfs_daddr_t             blkno,
+       int                     numblks,
+       xfs_buf_flags_t         flags,
+       struct xfs_buf          **bpp)
+{
+       struct xfs_buf_map      map = {
+               .bm_bn = blkno,
+               .bm_len = numblks,
+       };
+       return xfs_trans_read_buf_map(mp, tp, target, &map, 1, flags, bpp);
+}
+
 struct xfs_buf *xfs_trans_getsb(xfs_trans_t *, struct xfs_mount *, int);
 
 void           xfs_trans_brelse(xfs_trans_t *, struct xfs_buf *);
diff --git a/fs/xfs/xfs_trans_buf.c b/fs/xfs/xfs_trans_buf.c
index 21c5a5e..6311b99 100644
--- a/fs/xfs/xfs_trans_buf.c
+++ b/fs/xfs/xfs_trans_buf.c
@@ -41,20 +41,26 @@ STATIC struct xfs_buf *
 xfs_trans_buf_item_match(
        struct xfs_trans        *tp,
        struct xfs_buftarg      *target,
-       xfs_daddr_t             blkno,
-       int                     len)
+       struct xfs_buf_map      *map,
+       int                     nmaps)
 {
        struct xfs_log_item_desc *lidp;
        struct xfs_buf_log_item *blip;
+       int                     len = 0;
+       int                     i;
+
+       for (i = 0; i < nmaps; i++)
+               len += map[i].bm_len;
 
-       len = BBTOB(len);
        list_for_each_entry(lidp, &tp->t_items, lid_trans) {
                blip = (struct xfs_buf_log_item *)lidp->lid_item;
                if (blip->bli_item.li_type == XFS_LI_BUF &&
                    blip->bli_buf->b_target == target &&
-                   XFS_BUF_ADDR(blip->bli_buf) == blkno &&
-                   BBTOB(blip->bli_buf->b_length) == len)
+                   XFS_BUF_ADDR(blip->bli_buf) == map[0].bm_bn &&
+                   blip->bli_buf->b_length == len) {
+                       ASSERT(blip->bli_buf->b_map_count == nmaps);
                        return blip->bli_buf;
+               }
        }
 
        return NULL;
@@ -128,21 +134,19 @@ xfs_trans_bjoin(
  * If the transaction pointer is NULL, make this just a normal
  * get_buf() call.
  */
-xfs_buf_t *
-xfs_trans_get_buf(xfs_trans_t  *tp,
-                 xfs_buftarg_t *target_dev,
-                 xfs_daddr_t   blkno,
-                 int           len,
-                 uint          flags)
+struct xfs_buf *
+xfs_trans_get_buf_map(
+       struct xfs_trans        *tp,
+       struct xfs_buftarg      *target,
+       struct xfs_buf_map      *map,
+       int                     nmaps,
+       xfs_buf_flags_t         flags)
 {
        xfs_buf_t               *bp;
        xfs_buf_log_item_t      *bip;
 
-       /*
-        * Default to a normal get_buf() call if the tp is NULL.
-        */
-       if (tp == NULL)
-               return xfs_buf_get(target_dev, blkno, len, flags);
+       if (!tp)
+               return xfs_buf_get_map(target, map, nmaps, flags);
 
        /*
         * If we find the buffer in the cache with this transaction
@@ -150,7 +154,7 @@ xfs_trans_get_buf(xfs_trans_t       *tp,
         * have it locked.  In this case we just increment the lock
         * recursion count and return the buffer to the caller.
         */
-       bp = xfs_trans_buf_item_match(tp, target_dev, blkno, len);
+       bp = xfs_trans_buf_item_match(tp, target, map, nmaps);
        if (bp != NULL) {
                ASSERT(xfs_buf_islocked(bp));
                if (XFS_FORCED_SHUTDOWN(tp->t_mountp)) {
@@ -167,7 +171,7 @@ xfs_trans_get_buf(xfs_trans_t       *tp,
                return (bp);
        }
 
-       bp = xfs_buf_get(target_dev, blkno, len, flags);
+       bp = xfs_buf_get_map(target, map, nmaps, flags);
        if (bp == NULL) {
                return NULL;
        }
@@ -246,26 +250,22 @@ int       xfs_error_mod = 33;
  * read_buf() call.
  */
 int
-xfs_trans_read_buf(
-       xfs_mount_t     *mp,
-       xfs_trans_t     *tp,
-       xfs_buftarg_t   *target,
-       xfs_daddr_t     blkno,
-       int             len,
-       uint            flags,
-       xfs_buf_t       **bpp)
+xfs_trans_read_buf_map(
+       struct xfs_mount        *mp,
+       struct xfs_trans        *tp,
+       struct xfs_buftarg      *target,
+       struct xfs_buf_map      *map,
+       int                     nmaps,
+       xfs_buf_flags_t         flags,
+       struct xfs_buf          **bpp)
 {
        xfs_buf_t               *bp;
        xfs_buf_log_item_t      *bip;
        int                     error;
 
        *bpp = NULL;
-
-       /*
-        * Default to a normal get_buf() call if the tp is NULL.
-        */
-       if (tp == NULL) {
-               bp = xfs_buf_read(target, blkno, len, flags);
+       if (!tp) {
+               bp = xfs_buf_read_map(target, map, nmaps, flags);
                if (!bp)
                        return (flags & XBF_TRYLOCK) ?
                                        EAGAIN : XFS_ERROR(ENOMEM);
@@ -303,7 +303,7 @@ xfs_trans_read_buf(
         * If the buffer is not yet read in, then we read it in, increment
         * the lock recursion count, and return it to the caller.
         */
-       bp = xfs_trans_buf_item_match(tp, target, blkno, len);
+       bp = xfs_trans_buf_item_match(tp, target, map, nmaps);
        if (bp != NULL) {
                ASSERT(xfs_buf_islocked(bp));
                ASSERT(bp->b_transp == tp);
@@ -349,7 +349,7 @@ xfs_trans_read_buf(
                return 0;
        }
 
-       bp = xfs_buf_read(target, blkno, len, flags);
+       bp = xfs_buf_read_map(target, map, nmaps, flags);
        if (bp == NULL) {
                *bpp = NULL;
                return (flags & XBF_TRYLOCK) ?
-- 
1.7.10

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