xfs: add EOFBLOCKS inode tagging/untagging

Add the XFS_ICI_EOFBLOCKS_TAG inode tag to identify inodes with
speculatively preallocated blocks beyond EOF. An inode is tagged
when speculative preallocation occurs and untagged either via
truncate down or when post-EOF blocks are freed via release or
reclaim.

The tag management is intentionally not aggressive to prefer
simplicity over the complexity of handling all the corner cases
under which post-EOF blocks could be freed (i.e., forward
truncation, fallocate, write error conditions, etc.). This means
that a tagged inode may or may not have post-EOF blocks after a
period of time. The tag is eventually cleared when the inode is
released or reclaimed.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

1 files changed, 62 insertions, 0 deletions

diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index 9c8703b5cd72..f9afc5ff0482 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -1128,3 +1128,65 @@ xfs_reclaim_inodes_count(
         return reclaimable;
 }
 
+void
+xfs_inode_set_eofblocks_tag(
+        xfs_inode_t     *ip)
+{
+        struct xfs_mount *mp = ip->i_mount;
+        struct xfs_perag *pag;
+        int tagged;
+
+        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);
+
+        tagged = radix_tree_tagged(&pag->pag_ici_root,
+                                   XFS_ICI_EOFBLOCKS_TAG);
+        radix_tree_tag_set(&pag->pag_ici_root,
+                           XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino),
+                           XFS_ICI_EOFBLOCKS_TAG);
+        if (!tagged) {
+                /* propagate the eofblocks tag up into the perag radix tree */
+                spin_lock(&ip->i_mount->m_perag_lock);
+                radix_tree_tag_set(&ip->i_mount->m_perag_tree,
+                                   XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino),
+                                   XFS_ICI_EOFBLOCKS_TAG);
+                spin_unlock(&ip->i_mount->m_perag_lock);
+
+                trace_xfs_perag_set_eofblocks(ip->i_mount, pag->pag_agno,
+                                              -1, _RET_IP_);
+        }
+
+        spin_unlock(&pag->pag_ici_lock);
+        xfs_perag_put(pag);
+}
+
+void
+xfs_inode_clear_eofblocks_tag(
+        xfs_inode_t     *ip)
+{
+        struct xfs_mount *mp = ip->i_mount;
+        struct xfs_perag *pag;
+
+        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);
+
+        radix_tree_tag_clear(&pag->pag_ici_root,
+                             XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino),
+                             XFS_ICI_EOFBLOCKS_TAG);
+        if (!radix_tree_tagged(&pag->pag_ici_root, XFS_ICI_EOFBLOCKS_TAG)) {
+                /* clear the eofblocks tag from the perag radix tree */
+                spin_lock(&ip->i_mount->m_perag_lock);
+                radix_tree_tag_clear(&ip->i_mount->m_perag_tree,
+                                     XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino),
+                                     XFS_ICI_EOFBLOCKS_TAG);
+                spin_unlock(&ip->i_mount->m_perag_lock);
+                trace_xfs_perag_clear_eofblocks(ip->i_mount, pag->pag_agno,
+                                               -1, _RET_IP_);
+        }
+
+        spin_unlock(&pag->pag_ici_lock);
+        xfs_perag_put(pag);
+}
+