From: Darrick J. Wong <djwong@xxxxxxxxxx>
Alter the definition of i_prev_unlinked slightly to make it more obvious
when an inode with 0 link count is not part of the iunlink bucket lists
rooted in the AGI. The upcoming directory repair code needs to be able
to make this distinction to decide if a zero link count directory should
be moved to the orphanage or allowed to inactivate. An upcoming
enhancement to the online AGI fsck code will need this distinction to
check and rebuild the AGI unlinked buckets.
This distinction is necessary because it is not sufficient to check
inode.i_nlink to decide if an inode is on the unlinked list. Updates to
i_nlink can happen while holding only ILOCK_EXCL, but updates to an
inode's position in the AGI unlinked list (which happen after the nlink
update) requires both ILOCK_EXCL and the AGI buffer lock.
Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
fs/xfs/xfs_icache.c | 2 +-
fs/xfs/xfs_inode.c | 3 ++-
fs/xfs/xfs_inode.h | 20 +++++++++++++++++++-
3 files changed, 22 insertions(+), 3 deletions(-)
diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index 402f4b22de56..149e4c62b0c3 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -114,7 +114,7 @@ xfs_inode_alloc(
INIT_LIST_HEAD(&ip->i_ioend_list);
spin_lock_init(&ip->i_ioend_lock);
ip->i_next_unlinked = NULLAGINO;
- ip->i_prev_unlinked = NULLAGINO;
+ ip->i_prev_unlinked = 0;
return ip;
}
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 3af180a917b5..04c4cd6c4cda 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -2050,6 +2050,7 @@ xfs_iunlink_insert_inode(
}
/* Point the head of the list to point to this inode. */
+ ip->i_prev_unlinked = NULLAGINO;
return xfs_iunlink_update_bucket(tp, pag, agibp, bucket_index, agino);
}
@@ -2152,7 +2153,7 @@ xfs_iunlink_remove_inode(
}
ip->i_next_unlinked = NULLAGINO;
- ip->i_prev_unlinked = NULLAGINO;
+ ip->i_prev_unlinked = 0;
return error;
}
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index 56955f642288..3b8470c2db7b 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -68,8 +68,21 @@ typedef struct xfs_inode {
uint64_t i_diflags2; /* XFS_DIFLAG2_... */
struct timespec64 i_crtime; /* time created */
- /* unlinked list pointers */
+ /*
+ * Unlinked list pointers. These point to the next and previous inodes
+ * in the AGI unlinked bucket list, respectively. These fields can
+ * only be updated with the AGI locked.
+ *
+ * i_next_unlinked caches di_next_unlinked.
+ */
xfs_agino_t i_next_unlinked;
+
+ /*
+ * If the inode is not on an unlinked list, this field is zero. If the
+ * inode is the first element in an unlinked list, this field is
+ * NULLAGINO. Otherwise, i_prev_unlinked points to the previous inode
+ * in the unlinked list.
+ */
xfs_agino_t i_prev_unlinked;
/* VFS inode */
@@ -81,6 +94,11 @@ typedef struct xfs_inode {
struct list_head i_ioend_list;
} xfs_inode_t;
+static inline bool xfs_inode_on_unlinked_list(const struct xfs_inode *ip)
+{
+ return ip->i_prev_unlinked != 0;
+}
+
static inline bool xfs_inode_has_attr_fork(struct xfs_inode *ip)
{
return ip->i_forkoff > 0;
