On Mon, Dec 13, 2010 at 12:32:37PM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
>
> now that we are using RCU protection for the inode cache lookups,
> the lock is only needed on the modification side. Hence it is not
> necessary for the lock to be a rwlock as there are no read side
> holders anymore. Convert it to a spin lock to reflect it's exclusive
> nature.
Looks good!
Reviewed-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> Reviewed-by: Alex Elder <aelder@xxxxxxx>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> ---
> fs/xfs/linux-2.6/xfs_sync.c | 14 +++++++-------
> fs/xfs/xfs_ag.h | 2 +-
> fs/xfs/xfs_iget.c | 10 +++++-----
> fs/xfs/xfs_mount.c | 2 +-
> 4 files changed, 14 insertions(+), 14 deletions(-)
>
> diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c
> index 5ee02d7..d3b3b4f 100644
> --- a/fs/xfs/linux-2.6/xfs_sync.c
> +++ b/fs/xfs/linux-2.6/xfs_sync.c
> @@ -602,12 +602,12 @@ xfs_inode_set_reclaim_tag(
> struct xfs_perag *pag;
>
> pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
> - write_lock(&pag->pag_ici_lock);
> + spin_lock(&pag->pag_ici_lock);
> spin_lock(&ip->i_flags_lock);
> __xfs_inode_set_reclaim_tag(pag, ip);
> __xfs_iflags_set(ip, XFS_IRECLAIMABLE);
> spin_unlock(&ip->i_flags_lock);
> - write_unlock(&pag->pag_ici_lock);
> + spin_unlock(&pag->pag_ici_lock);
> xfs_perag_put(pag);
> }
>
> @@ -808,12 +808,12 @@ reclaim:
> * added to the tree assert that it's been there before to catch
> * problems with the inode life time early on.
> */
> - write_lock(&pag->pag_ici_lock);
> + spin_lock(&pag->pag_ici_lock);
> if (!radix_tree_delete(&pag->pag_ici_root,
> XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino)))
> ASSERT(0);
> __xfs_inode_clear_reclaim(pag, ip);
> - write_unlock(&pag->pag_ici_lock);
> + spin_unlock(&pag->pag_ici_lock);
>
> /*
> * Here we do an (almost) spurious inode lock in order to coordinate
> @@ -877,14 +877,14 @@ restart:
> struct xfs_inode *batch[XFS_LOOKUP_BATCH];
> int i;
>
> - write_lock(&pag->pag_ici_lock);
> + spin_lock(&pag->pag_ici_lock);
> nr_found = radix_tree_gang_lookup_tag(
> &pag->pag_ici_root,
> (void **)batch, first_index,
> XFS_LOOKUP_BATCH,
> XFS_ICI_RECLAIM_TAG);
> if (!nr_found) {
> - write_unlock(&pag->pag_ici_lock);
> + spin_unlock(&pag->pag_ici_lock);
> break;
> }
>
> @@ -911,7 +911,7 @@ restart:
> }
>
> /* unlock now we've grabbed the inodes. */
> - write_unlock(&pag->pag_ici_lock);
> + spin_unlock(&pag->pag_ici_lock);
>
> for (i = 0; i < nr_found; i++) {
> if (!batch[i])
> diff --git a/fs/xfs/xfs_ag.h b/fs/xfs/xfs_ag.h
> index 63c7a1a..58632cc 100644
> --- a/fs/xfs/xfs_ag.h
> +++ b/fs/xfs/xfs_ag.h
> @@ -227,7 +227,7 @@ typedef struct xfs_perag {
>
> atomic_t pagf_fstrms; /* # of filestreams active in this AG */
>
> - rwlock_t pag_ici_lock; /* incore inode lock */
> + spinlock_t pag_ici_lock; /* incore inode cache lock */
> struct radix_tree_root pag_ici_root; /* incore inode cache root */
> int pag_ici_reclaimable; /* reclaimable inodes */
> struct mutex pag_ici_reclaim_lock; /* serialisation point */
> diff --git a/fs/xfs/xfs_iget.c b/fs/xfs/xfs_iget.c
> index 1e3b035..ec440da 100644
> --- a/fs/xfs/xfs_iget.c
> +++ b/fs/xfs/xfs_iget.c
> @@ -263,7 +263,7 @@ xfs_iget_cache_hit(
> goto out_error;
> }
>
> - write_lock(&pag->pag_ici_lock);
> + spin_lock(&pag->pag_ici_lock);
> spin_lock(&ip->i_flags_lock);
> ip->i_flags &= ~(XFS_IRECLAIMABLE | XFS_IRECLAIM);
> ip->i_flags |= XFS_INEW;
> @@ -276,7 +276,7 @@ xfs_iget_cache_hit(
> &xfs_iolock_active, "xfs_iolock_active");
>
> spin_unlock(&ip->i_flags_lock);
> - write_unlock(&pag->pag_ici_lock);
> + spin_unlock(&pag->pag_ici_lock);
> } else {
> /* If the VFS inode is being torn down, pause and try again. */
> if (!igrab(inode)) {
> @@ -354,7 +354,7 @@ xfs_iget_cache_miss(
> BUG();
> }
>
> - write_lock(&pag->pag_ici_lock);
> + spin_lock(&pag->pag_ici_lock);
>
> /* insert the new inode */
> error = radix_tree_insert(&pag->pag_ici_root, agino, ip);
> @@ -369,14 +369,14 @@ xfs_iget_cache_miss(
> ip->i_udquot = ip->i_gdquot = NULL;
> xfs_iflags_set(ip, XFS_INEW);
>
> - write_unlock(&pag->pag_ici_lock);
> + spin_unlock(&pag->pag_ici_lock);
> radix_tree_preload_end();
>
> *ipp = ip;
> return 0;
>
> out_preload_end:
> - write_unlock(&pag->pag_ici_lock);
> + spin_unlock(&pag->pag_ici_lock);
> radix_tree_preload_end();
> if (lock_flags)
> xfs_iunlock(ip, lock_flags);
> diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
> index fe27338..52186c0 100644
> --- a/fs/xfs/xfs_mount.c
> +++ b/fs/xfs/xfs_mount.c
> @@ -598,7 +598,7 @@ xfs_initialize_perag(
> goto out_unwind;
> pag->pag_agno = index;
> pag->pag_mount = mp;
> - rwlock_init(&pag->pag_ici_lock);
> + spin_lock_init(&pag->pag_ici_lock);
> mutex_init(&pag->pag_ici_reclaim_lock);
> INIT_RADIX_TREE(&pag->pag_ici_root, GFP_ATOMIC);
> spin_lock_init(&pag->pag_buf_lock);
> --
> 1.7.2.3
>
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