[PATCH 04/11] xfs: decide if inode needs inactivation

Darrick J. Wong
2021-03-11T03:06:35Z

From: Darrick J. Wong <djwong@kernel.org>

Add a predicate function to decide if an inode needs (deferred)
inactivation. Any file that has been unlinked or has speculative
preallocations either for post-EOF writes or for CoW qualifies.
This function will also be used by the upcoming deferred inactivation
patch.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
fs/xfs/xfs_inode.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++++
fs/xfs/xfs_inode.h | 2 ++
2 files changed, 65 insertions(+)

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 12c79962f8c3..65897cb0cf2a 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -1665,6 +1665,69 @@ xfs_inactive_ifree(
return 0;
}

+/*
+ * Returns true if we need to update the on-disk metadata before we can free
+ * the memory used by this inode. Updates include freeing post-eof
+ * preallocations; freeing COW staging extents; and marking the inode free in
+ * the inobt if it is on the unlinked list.
+ */
+bool
+xfs_inode_needs_inactivation(
+ struct xfs_inode *ip)
+{
+ struct xfs_mount *mp = ip->i_mount;
+ struct xfs_ifork *cow_ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
+
+ /*
+ * If the inode is already free, then there can be nothing
+ * to clean up here.
+ */
+ if (VFS_I(ip)->i_mode == 0)
+ return false;
+
+ /* If this is a read-only mount, don't do this (would generate I/O) */
+ if (mp->m_flags & XFS_MOUNT_RDONLY)
+ return false;
+
+ /* Metadata inodes require explicit resource cleanup. */
+ if (xfs_is_metadata_inode(ip))
+ return false;
+
+ /* Try to clean out the cow blocks if there are any. */
+ if (cow_ifp && cow_ifp->if_bytes > 0)
+ return true;
+
+ if (VFS_I(ip)->i_nlink != 0) {
+ int error;
+ bool has;
+
+ /*
+ * force is true because we are evicting an inode from the
+ * cache. Post-eof blocks must be freed, lest we end up with
+ * broken free space accounting.
+ *
+ * Note: don't bother with iolock here since lockdep complains
+ * about acquiring it in reclaim context. We have the only
+ * reference to the inode at this point anyways.
+ *
+ * If the predicate errors out, send the inode through
+ * inactivation anyway, because that's what we did before.
+ * The inactivation worker will ignore an inode that doesn't
+ * actually need it.
+ */
+ if (!xfs_can_free_eofblocks(ip, true))
+ return false;
+ error = xfs_has_eofblocks(ip, &has);
+ return error != 0 || has;
+ }
+
+ /*
+ * Link count dropped to zero, which means we have to mark the inode
+ * free on disk and remove it from the AGI unlinked list.
+ */
+ return true;
+}
+
/*
* xfs_inactive
*
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index c2c26f8f4a81..3fe8c8afbc72 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -480,6 +480,8 @@ extern struct kmem_zone *xfs_inode_zone;
/* The default CoW extent size hint. */
#define XFS_DEFAULT_COWEXTSZ_HINT 32

+bool xfs_inode_needs_inactivation(struct xfs_inode *ip);
+
int xfs_iunlink_init(struct xfs_perag *pag);
void xfs_iunlink_destroy(struct xfs_perag *pag);