libxfs: introduce libxfs_buf_read_uncached

Introduce an uncached read function so that userspace can handle them in
the same way as the kernel.  This also eliminates the need for some of
the libxfs_purgebuf calls (and two trips into the cache code).

Refactor the get/read uncached buffer functions to hide the details of
uncached buffer-ism in rdwr.c.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>

diff --git a/libxfs/libxfs_api_defs.h b/libxfs/libxfs_api_defs.h
index df267c98a21c333066045437bc712499d4f92ac7..1149e301f4d7fe6db118ade13e12c29d54047734 100644 (file)
--- a/libxfs/libxfs_api_defs.h
+++ b/libxfs/libxfs_api_defs.h
@@ -45,7 +45,9 @@
 #define xfs_btree_init_block           libxfs_btree_init_block
 #define xfs_buf_delwri_submit          libxfs_buf_delwri_submit
 #define xfs_buf_get                    libxfs_buf_get
+#define xfs_buf_get_uncached           libxfs_buf_get_uncached
 #define xfs_buf_read                   libxfs_buf_read
+#define xfs_buf_read_uncached          libxfs_buf_read_uncached
 #define xfs_buf_relse                  libxfs_buf_relse
 #define xfs_bunmapi                    libxfs_bunmapi
 #define xfs_bwrite                     libxfs_bwrite

diff --git a/libxfs/libxfs_io.h b/libxfs/libxfs_io.h
index d96b5318eaad152ea63605bbbb2acff7163ba8e5..21afc99c1d45f293dd4d976d22de4c1b3d499da9 100644 (file)
--- a/libxfs/libxfs_io.h
+++ b/libxfs/libxfs_io.h
@@ -255,23 +255,11 @@ xfs_buf_associate_memory(struct xfs_buf *bp, void *mem, size_t len)
        return 0;
 }
 
-/*
- * Allocate an uncached buffer that points nowhere.  The refcount will be 1,
- * and the cache node hash list will be empty to indicate that it's uncached.
- */
-static inline struct xfs_buf *
-xfs_buf_get_uncached(struct xfs_buftarg *targ, size_t bblen, int flags)
-{
-       struct xfs_buf  *bp;
-
-       bp = libxfs_getbufr(targ, XFS_BUF_DADDR_NULL, bblen);
-       if (!bp)
-               return NULL;
-
-       INIT_LIST_HEAD(&bp->b_node.cn_hash);
-       bp->b_node.cn_count = 1;
-       return bp;
-}
+struct xfs_buf *libxfs_buf_get_uncached(struct xfs_buftarg *targ, size_t bblen,
+               int flags);
+int libxfs_buf_read_uncached(struct xfs_buftarg *targ, xfs_daddr_t daddr,
+               size_t bblen, int flags, struct xfs_buf **bpp,
+               const struct xfs_buf_ops *ops);
 
 /* Push a single buffer on a delwri queue. */
 static inline void

diff --git a/libxfs/rdwr.c b/libxfs/rdwr.c
index 2c67edded4afc87564fd7ec5bbcd2bfc05c189a0..3b4702664efc17fc4e4286c3ac28bdd43fe026e1 100644 (file)
--- a/libxfs/rdwr.c
+++ b/libxfs/rdwr.c
@@ -1073,6 +1073,73 @@ libxfs_readbuf_map(struct xfs_buftarg *btp, struct xfs_buf_map *map, int nmaps,
        return bp;
 }
 
+/* Allocate a raw uncached buffer. */
+static inline struct xfs_buf *
+libxfs_getbufr_uncached(
+       struct xfs_buftarg      *targ,
+       xfs_daddr_t             daddr,
+       size_t                  bblen)
+{
+       struct xfs_buf          *bp;
+
+       bp = libxfs_getbufr(targ, daddr, bblen);
+       if (!bp)
+               return NULL;
+
+       INIT_LIST_HEAD(&bp->b_node.cn_hash);
+       bp->b_node.cn_count = 1;
+       return bp;
+}
+
+/*
+ * Allocate an uncached buffer that points nowhere.  The refcount will be 1,
+ * and the cache node hash list will be empty to indicate that it's uncached.
+ */
+struct xfs_buf *
+libxfs_buf_get_uncached(
+       struct xfs_buftarg      *targ,
+       size_t                  bblen,
+       int                     flags)
+{
+       return libxfs_getbufr_uncached(targ, XFS_BUF_DADDR_NULL, bblen);
+}
+
+/*
+ * Allocate and read an uncached buffer.  The refcount will be 1, and the cache
+ * node hash list will be empty to indicate that it's uncached.
+ */
+int
+libxfs_buf_read_uncached(
+       struct xfs_buftarg      *targ,
+       xfs_daddr_t             daddr,
+       size_t                  bblen,
+       int                     flags,
+       struct xfs_buf          **bpp,
+       const struct xfs_buf_ops *ops)
+{
+       struct xfs_buf          *bp;
+       int                     error;
+
+       *bpp = NULL;
+       bp = libxfs_getbufr_uncached(targ, daddr, bblen);
+       if (!bp)
+               return -ENOMEM;
+
+       error = libxfs_readbufr(targ, daddr, bp, bblen, flags);
+       if (error)
+               goto err;
+
+       error = libxfs_readbuf_verify(bp, ops);
+       if (error)
+               goto err;
+
+       *bpp = bp;
+       return 0;
+err:
+       libxfs_buf_relse(bp);
+       return error;
+}
+
 static int
 __write_buf(int fd, void *buf, int len, off64_t offset, int flags)
 {