From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Currently, uncached buffers in userspace are created with zero refcount
and are fed to cache_node_put when they're released. This is totally
broken -- the refcount should be 1 (because the caller now holds a
reference) and we should never be dumping uncached buffers into the
cache. Fix both of these problems.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
---
libxfs/libxfs_io.h | 18 ++++++++++++++++++
libxfs/libxfs_priv.h | 2 --
libxfs/rdwr.c | 5 ++++-
3 files changed, 22 insertions(+), 3 deletions(-)
diff --git a/libxfs/libxfs_io.h b/libxfs/libxfs_io.h
index 0b8d9774..7dcb4bff 100644
--- a/libxfs/libxfs_io.h
+++ b/libxfs/libxfs_io.h
@@ -227,4 +227,22 @@ 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;
+}
+
#endif /* __LIBXFS_IO_H__ */
diff --git a/libxfs/libxfs_priv.h b/libxfs/libxfs_priv.h
index 96d74bfa..b05e082a 100644
--- a/libxfs/libxfs_priv.h
+++ b/libxfs/libxfs_priv.h
@@ -379,8 +379,6 @@ roundup_64(uint64_t x, uint32_t y)
(len) = __bar; /* no set-but-unused warning */ \
NULL; \
})
-#define xfs_buf_get_uncached(t,n,f) \
- libxfs_getbufr((t), XFS_BUF_DADDR_NULL, (n));
#define xfs_buf_relse(bp) libxfs_putbuf(bp)
#define xfs_buf_get(devp,blkno,len) (libxfs_getbuf((devp), (blkno), (len)))
#define xfs_bwrite(bp) libxfs_writebuf((bp), 0)
diff --git a/libxfs/rdwr.c b/libxfs/rdwr.c
index 1f2c129b..3282f6de 100644
--- a/libxfs/rdwr.c
+++ b/libxfs/rdwr.c
@@ -867,7 +867,10 @@ libxfs_putbuf(xfs_buf_t *bp)
}
}
- cache_node_put(libxfs_bcache, (struct cache_node *)bp);
+ if (!list_empty(&bp->b_node.cn_hash))
+ cache_node_put(libxfs_bcache, (struct cache_node *)bp);
+ else if (--bp->b_node.cn_count == 0)
+ libxfs_putbufr(bp);
}
void
