diff options
| author | Dave Chinner <dchinner@redhat.com> | 2010-09-24 21:58:31 +1000 |
|---|---|---|
| committer | Alex Elder <aelder@sgi.com> | 2010-10-18 15:07:47 -0500 |
| commit | 5adc94c247c3779782c7b0b8b5e28cf50596eb37 (patch) | |
| tree | 95c2fac56cf6b9559b70aeaa43dae5a18b3c3fec /fs/xfs | |
| parent | 686865f76e35b28ba7aa6afa19209426f0da6201 (diff) | |
xfs: introduced uncached buffer read primitve
To avoid the need to use cached buffers for single-shot or buffers
cached at the filesystem level, introduce a new buffer read
primitive that bypasses the cache an reads directly from disk.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>
Diffstat (limited to 'fs/xfs')
| -rw-r--r-- | fs/xfs/linux-2.6/xfs_buf.c | 34 | ||||
| -rw-r--r-- | fs/xfs/linux-2.6/xfs_buf.h | 3 |
2 files changed, 37 insertions, 0 deletions
diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c index eca945b0f88f..22c7bff77ad2 100644 --- a/fs/xfs/linux-2.6/xfs_buf.c +++ b/fs/xfs/linux-2.6/xfs_buf.c @@ -638,6 +638,40 @@ xfs_buf_readahead( xfs_buf_read(target, ioff, isize, flags); } +/* + * Read an uncached buffer from disk. Allocates and returns a locked + * buffer containing the disk contents or nothing. + */ +struct xfs_buf * +xfs_buf_read_uncached( + struct xfs_mount *mp, + struct xfs_buftarg *target, + xfs_daddr_t daddr, + size_t length, + int flags) +{ + xfs_buf_t *bp; + int error; + + bp = xfs_buf_get_uncached(target, length, flags); + if (!bp) + return NULL; + + /* set up the buffer for a read IO */ + xfs_buf_lock(bp); + XFS_BUF_SET_ADDR(bp, daddr); + XFS_BUF_READ(bp); + XFS_BUF_BUSY(bp); + + xfsbdstrat(mp, bp); + error = xfs_iowait(bp); + if (error || bp->b_error) { + xfs_buf_relse(bp); + return NULL; + } + return bp; +} + xfs_buf_t * xfs_buf_get_empty( size_t len, diff --git a/fs/xfs/linux-2.6/xfs_buf.h b/fs/xfs/linux-2.6/xfs_buf.h index fb30447091d8..57eedc750ee6 100644 --- a/fs/xfs/linux-2.6/xfs_buf.h +++ b/fs/xfs/linux-2.6/xfs_buf.h @@ -218,6 +218,9 @@ extern int xfs_buf_associate_memory(xfs_buf_t *, void *, size_t); extern void xfs_buf_hold(xfs_buf_t *); extern void xfs_buf_readahead(xfs_buftarg_t *, xfs_off_t, size_t, xfs_buf_flags_t); +struct xfs_buf *xfs_buf_read_uncached(struct xfs_mount *mp, + struct xfs_buftarg *target, + xfs_daddr_t daddr, size_t length, int flags); /* Releasing Buffers */ extern void xfs_buf_free(xfs_buf_t *); |