From: Darrick J. Wong <djwong@xxxxxxxxxx>
If the trylock-based dirent check fails, retain those parent pointers
and check them at the end. This may involve dropping the locks on the
file being scanned, so yay.
Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
libxfs/xfs_parent.c | 38 ++++++++++++++++++++++++++++++++++++++
libxfs/xfs_parent.h | 10 ++++++++++
2 files changed, 48 insertions(+)
diff --git a/libxfs/xfs_parent.c b/libxfs/xfs_parent.c
index 980f0b82..1598158f 100644
--- a/libxfs/xfs_parent.c
+++ b/libxfs/xfs_parent.c
@@ -299,3 +299,41 @@ xfs_pptr_calc_space_res(
XFS_NEXTENTADD_SPACE_RES(mp, namelen, XFS_ATTR_FORK);
}
+/*
+ * Look up the @name associated with the parent pointer (@pptr) of @ip. Caller
+ * must hold at least ILOCK_SHARED. Returns the length of the dirent name, or
+ * a negative errno. The scratchpad need not be initialized.
+ */
+int
+xfs_parent_lookup(
+ struct xfs_trans *tp,
+ struct xfs_inode *ip,
+ const struct xfs_parent_name_irec *pptr,
+ unsigned char *name,
+ unsigned int namelen,
+ struct xfs_parent_scratch *scr)
+{
+ int error;
+
+ xfs_parent_irec_to_disk(&scr->rec, NULL, NULL, pptr);
+
+ memset(&scr->args, 0, sizeof(struct xfs_da_args));
+ scr->args.attr_filter = XFS_ATTR_PARENT;
+ scr->args.dp = ip;
+ scr->args.geo = ip->i_mount->m_attr_geo;
+ scr->args.name = (const unsigned char *)&scr->rec;
+ scr->args.namelen = sizeof(struct xfs_parent_name_rec);
+ scr->args.op_flags = XFS_DA_OP_OKNOENT;
+ scr->args.trans = tp;
+ scr->args.valuelen = namelen;
+ scr->args.value = name;
+ scr->args.whichfork = XFS_ATTR_FORK;
+
+ scr->args.hashval = xfs_da_hashname(scr->args.name, scr->args.namelen);
+
+ error = xfs_attr_get_ilocked(&scr->args);
+ if (error)
+ return error;
+
+ return scr->args.valuelen;
+}
diff --git a/libxfs/xfs_parent.h b/libxfs/xfs_parent.h
index 4eb92fb4..cd1b1351 100644
--- a/libxfs/xfs_parent.h
+++ b/libxfs/xfs_parent.h
@@ -103,4 +103,14 @@ xfs_parent_finish(
unsigned int xfs_pptr_calc_space_res(struct xfs_mount *mp,
unsigned int namelen);
+/* Scratchpad memory so that raw parent operations don't burn stack space. */
+struct xfs_parent_scratch {
+ struct xfs_parent_name_rec rec;
+ struct xfs_da_args args;
+};
+
+int xfs_parent_lookup(struct xfs_trans *tp, struct xfs_inode *ip,
+ const struct xfs_parent_name_irec *pptr, unsigned char *name,
+ unsigned int namelen, struct xfs_parent_scratch *scratch);
+
#endif /* __XFS_PARENT_H__ */
