xfs: make xfs_inode_set_eofblocks_tag cheaper for the common case

For long growing file writes we will usually already have the
eofblocks tag set when adding more speculative preallocations.  Add
a flag in the inode to allow us to skip the the fairly expensive
AG-wide spinlocks and multiple radix tree operations in that case.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

2 files changed, 15 insertions, 0 deletions

diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index fb39a66914dd..65b2e3f85f52 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -1414,6 +1414,16 @@ xfs_inode_set_eofblocks_tag(
         struct xfs_perag *pag;
         int tagged;
 
+        /*
+         * Don't bother locking the AG and looking up in the radix trees
+         * if we already know that we have the tag set.
+         */
+        if (ip->i_flags & XFS_IEOFBLOCKS)
+                return;
+        spin_lock(&ip->i_flags_lock);
+        ip->i_flags |= XFS_IEOFBLOCKS;
+        spin_unlock(&ip->i_flags_lock);
+
         pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
         spin_lock(&pag->pag_ici_lock);
         trace_xfs_inode_set_eofblocks_tag(ip);
@@ -1449,6 +1459,10 @@ xfs_inode_clear_eofblocks_tag(
         struct xfs_mount *mp = ip->i_mount;
         struct xfs_perag *pag;
 
+        spin_lock(&ip->i_flags_lock);
+        ip->i_flags &= ~XFS_IEOFBLOCKS;
+        spin_unlock(&ip->i_flags_lock);
+
         pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
         spin_lock(&pag->pag_ici_lock);
         trace_xfs_inode_clear_eofblocks_tag(ip);
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index e1a411e08f00..8f30d2533b48 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -216,6 +216,7 @@ xfs_get_initial_prid(struct xfs_inode *dp)
 #define __XFS_IPINNED_BIT       8        /* wakeup key for zero pin count */
 #define XFS_IPINNED             (1 << __XFS_IPINNED_BIT)
 #define XFS_IDONTCACHE          (1 << 9) /* don't cache the inode long term */
+#define XFS_IEOFBLOCKS          (1 << 10)/* has the preallocblocks tag set */
 
 /*
  * Per-lifetime flags need to be reset when re-using a reclaimable inode during