xfs: store xfs_mount in the buftarg instead of in the xfs_buf

Each buffer contains both a buftarg pointer and a mount pointer. If
we add a mount pointer into the buftarg, we can avoid needing the
b_mount field in every buffer and grab it from the buftarg when
needed instead. This shrinks the xfs_buf by 8 bytes.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>

diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c
index 22c7bff..d692897 100644 (file)
--- a/fs/xfs/linux-2.6/xfs_buf.c
+++ b/fs/xfs/linux-2.6/xfs_buf.c
@@ -894,7 +894,7 @@ xfs_buf_lock(
        trace_xfs_buf_lock(bp, _RET_IP_);
 
        if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE))
-               xfs_log_force(bp->b_mount, 0);
+               xfs_log_force(bp->b_target->bt_mount, 0);
        if (atomic_read(&bp->b_io_remaining))
                blk_run_address_space(bp->b_target->bt_mapping);
        down(&bp->b_sema);
@@ -1017,7 +1017,6 @@ xfs_bwrite(
 {
        int                     error;
 
-       bp->b_mount = mp;
        bp->b_flags |= XBF_WRITE;
        bp->b_flags &= ~(XBF_ASYNC | XBF_READ);
 
@@ -1038,8 +1037,6 @@ xfs_bdwrite(
 {
        trace_xfs_buf_bdwrite(bp, _RET_IP_);
 
-       bp->b_mount = mp;
-
        bp->b_flags &= ~XBF_READ;
        bp->b_flags |= (XBF_DELWRI | XBF_ASYNC);
 
@@ -1128,7 +1125,7 @@ int
 xfs_bdstrat_cb(
        struct xfs_buf  *bp)
 {
-       if (XFS_FORCED_SHUTDOWN(bp->b_mount)) {
+       if (XFS_FORCED_SHUTDOWN(bp->b_target->bt_mount)) {
                trace_xfs_bdstrat_shut(bp, _RET_IP_);
                /*
                 * Metadata write that didn't get logged but
@@ -1644,6 +1641,7 @@ out_error:
 
 xfs_buftarg_t *
 xfs_alloc_buftarg(
+       struct xfs_mount        *mp,
        struct block_device     *bdev,
        int                     external,
        const char              *fsname)
@@ -1652,6 +1650,7 @@ xfs_alloc_buftarg(
 
        btp = kmem_zalloc(sizeof(*btp), KM_SLEEP);
 
+       btp->bt_mount = mp;
        btp->bt_dev =  bdev->bd_dev;
        btp->bt_bdev = bdev;
        if (xfs_setsize_buftarg_early(btp, bdev))

diff --git a/fs/xfs/linux-2.6/xfs_buf.h b/fs/xfs/linux-2.6/xfs_buf.h
index 57eedc7..def2cea 100644 (file)
--- a/fs/xfs/linux-2.6/xfs_buf.h
+++ b/fs/xfs/linux-2.6/xfs_buf.h
@@ -132,6 +132,7 @@ typedef struct xfs_buftarg {
        dev_t                   bt_dev;
        struct block_device     *bt_bdev;
        struct address_space    *bt_mapping;
+       struct xfs_mount        *bt_mount;
        unsigned int            bt_bsize;
        unsigned int            bt_sshift;
        size_t                  bt_smask;
@@ -189,7 +190,6 @@ typedef struct xfs_buf {
        struct completion       b_iowait;       /* queue for I/O waiters */
        void                    *b_fspriv;
        void                    *b_fspriv2;
-       struct xfs_mount        *b_mount;
        unsigned short          b_error;        /* error code on I/O */
        unsigned int            b_page_count;   /* size of page array */
        unsigned int            b_offset;       /* page offset in first page */
@@ -377,7 +377,8 @@ static inline void xfs_buf_relse(xfs_buf_t *bp)
 /*
  *     Handling of buftargs.
  */
-extern xfs_buftarg_t *xfs_alloc_buftarg(struct block_device *, int, const char *);
+extern xfs_buftarg_t *xfs_alloc_buftarg(struct xfs_mount *,
+                       struct block_device *, int, const char *);
 extern void xfs_free_buftarg(struct xfs_mount *, struct xfs_buftarg *);
 extern void xfs_wait_buftarg(xfs_buftarg_t *);
 extern int xfs_setsize_buftarg(xfs_buftarg_t *, unsigned int, unsigned int);

diff --git a/fs/xfs/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c
index 83154c0..4759be4 100644 (file)
--- a/fs/xfs/linux-2.6/xfs_super.c
+++ b/fs/xfs/linux-2.6/xfs_super.c
@@ -758,18 +758,20 @@ xfs_open_devices(
         * Setup xfs_mount buffer target pointers
         */
        error = ENOMEM;
-       mp->m_ddev_targp = xfs_alloc_buftarg(ddev, 0, mp->m_fsname);
+       mp->m_ddev_targp = xfs_alloc_buftarg(mp, ddev, 0, mp->m_fsname);
        if (!mp->m_ddev_targp)
                goto out_close_rtdev;
 
        if (rtdev) {
-               mp->m_rtdev_targp = xfs_alloc_buftarg(rtdev, 1, mp->m_fsname);
+               mp->m_rtdev_targp = xfs_alloc_buftarg(mp, rtdev, 1,
+                                                       mp->m_fsname);
                if (!mp->m_rtdev_targp)
                        goto out_free_ddev_targ;
        }
 
        if (logdev && logdev != ddev) {
-               mp->m_logdev_targp = xfs_alloc_buftarg(logdev, 1, mp->m_fsname);
+               mp->m_logdev_targp = xfs_alloc_buftarg(mp, logdev, 1,
+                                                       mp->m_fsname);
                if (!mp->m_logdev_targp)
                        goto out_free_rtdev_targ;
        } else {

diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
index 1b09d7a..ee75576 100644 (file)
--- a/fs/xfs/xfs_buf_item.c
+++ b/fs/xfs/xfs_buf_item.c
@@ -692,8 +692,7 @@ xfs_buf_item_init(
         * the first.  If we do already have one, there is
         * nothing to do here so return.
         */
-       if (bp->b_mount != mp)
-               bp->b_mount = mp;
+       ASSERT(bp->b_target->bt_mount == mp);
        if (XFS_BUF_FSPRIVATE(bp, void *) != NULL) {
                lip = XFS_BUF_FSPRIVATE(bp, xfs_log_item_t *);
                if (lip->li_type == XFS_LI_BUF) {

diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 3d88754..351d711 100644 (file)
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -322,10 +322,11 @@ xlog_recover_iodone(
                 * this during recovery. One strike!
                 */
                xfs_ioerror_alert("xlog_recover_iodone",
-                                 bp->b_mount, bp, XFS_BUF_ADDR(bp));
-               xfs_force_shutdown(bp->b_mount, SHUTDOWN_META_IO_ERROR);
+                                       bp->b_target->bt_mount, bp,
+                                       XFS_BUF_ADDR(bp));
+               xfs_force_shutdown(bp->b_target->bt_mount,
+                                       SHUTDOWN_META_IO_ERROR);
        }
-       bp->b_mount = NULL;
        XFS_BUF_CLR_IODONE_FUNC(bp);
        xfs_biodone(bp);
 }
@@ -2276,8 +2277,7 @@ xlog_recover_do_buffer_trans(
                XFS_BUF_STALE(bp);
                error = xfs_bwrite(mp, bp);
        } else {
-               ASSERT(bp->b_mount == NULL || bp->b_mount == mp);
-               bp->b_mount = mp;
+               ASSERT(bp->b_target->bt_mount == mp);
                XFS_BUF_SET_IODONE_FUNC(bp, xlog_recover_iodone);
                xfs_bdwrite(mp, bp);
        }
@@ -2541,8 +2541,7 @@ xlog_recover_do_inode_trans(
        }
 
 write_inode_buffer:
-       ASSERT(bp->b_mount == NULL || bp->b_mount == mp);
-       bp->b_mount = mp;
+       ASSERT(bp->b_target->bt_mount == mp);
        XFS_BUF_SET_IODONE_FUNC(bp, xlog_recover_iodone);
        xfs_bdwrite(mp, bp);
 error:
@@ -2679,8 +2678,7 @@ xlog_recover_do_dquot_trans(
        memcpy(ddq, recddq, item->ri_buf[1].i_len);
 
        ASSERT(dq_f->qlf_size == 2);
-       ASSERT(bp->b_mount == NULL || bp->b_mount == mp);
-       bp->b_mount = mp;
+       ASSERT(bp->b_target->bt_mount == mp);
        XFS_BUF_SET_IODONE_FUNC(bp, xlog_recover_iodone);
        xfs_bdwrite(mp, bp);