Author: asomers
Date: Sat May 11 03:38:50 2019
New Revision: 347480
URL: https://svnweb.freebsd.org/changeset/base/347480
Log:
MFC r346078:
fix cache_lookup's documentation
cache_lookup's documentation got dislocated by r324378. Relocate and expand
it.
Reviewed by: jhb, kib
Sponsored by: The FreeBSD Foundation
Modified:
stable/11/sys/kern/vfs_cache.c
Directory Properties:
stable/11/ (props changed)
Modified: stable/11/sys/kern/vfs_cache.c
==============================================================================
--- stable/11/sys/kern/vfs_cache.c Sat May 11 03:37:43 2019
(r347479)
+++ stable/11/sys/kern/vfs_cache.c Sat May 11 03:38:50 2019
(r347480)
@@ -143,7 +143,7 @@ struct namecache_ts {
* Names found by directory scans are retained in a cache
* for future reference. It is managed LRU, so frequently
* used names will hang around. Cache is indexed by hash value
- * obtained from (vp, name) where vp refers to the directory
+ * obtained from (dvp, name) where dvp refers to the directory
* containing name.
*
* If it is a "negative" entry, (i.e. for a name that is known NOT to
@@ -1121,23 +1121,6 @@ cache_lookup_dot(struct vnode *dvp, struct vnode **vpp
return (-1);
}
-/*
- * Lookup an entry in the cache
- *
- * Lookup is called with dvp pointing to the directory to search,
- * cnp pointing to the name of the entry being sought. If the lookup
- * succeeds, the vnode is returned in *vpp, and a status of -1 is
- * returned. If the lookup determines that the name does not exist
- * (negative caching), a status of ENOENT is returned. If the lookup
- * fails, a status of zero is returned. If the directory vnode is
- * recycled out from under us due to a forced unmount, a status of
- * ENOENT is returned.
- *
- * vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is
- * unlocked. If we're looking up . an extra ref is taken, but the lock is
- * not recursively acquired.
- */
-
static __noinline int
cache_lookup_nomakeentry(struct vnode *dvp, struct vnode **vpp,
struct componentname *cnp, struct timespec *tsp, int *ticksp)
@@ -1221,6 +1204,42 @@ out_no_entry:
return (0);
}
+/**
+ * Lookup a name in the name cache
+ *
+ * # Arguments
+ *
+ * - dvp: Parent directory in which to search.
+ * - vpp: Return argument. Will contain desired vnode on cache hit.
+ * - cnp: Parameters of the name search. The most interesting bits of
+ * the cn_flags field have the following meanings:
+ * - MAKEENTRY: If clear, free an entry from the cache rather than look
+ * it up.
+ * - ISDOTDOT: Must be set if and only if cn_nameptr == ".."
+ * - tsp: Return storage for cache timestamp. On a successful (positive
+ * or negative) lookup, tsp will be filled with any timespec that
+ * was stored when this cache entry was created. However, it will
+ * be clear for "." entries.
+ * - ticks: Return storage for alternate cache timestamp. On a successful
+ * (positive or negative) lookup, it will contain the ticks value
+ * that was current when the cache entry was created, unless cnp
+ * was ".".
+ *
+ * # Returns
+ *
+ * - -1: A positive cache hit. vpp will contain the desired vnode.
+ * - ENOENT: A negative cache hit, or dvp was recycled out from under us due
+ * to a forced unmount. vpp will not be modified. If the entry
+ * is a whiteout, then the ISWHITEOUT flag will be set in
+ * cnp->cn_flags.
+ * - 0: A cache miss. vpp will not be modified.
+ *
+ * # Locking
+ *
+ * On a cache hit, vpp will be returned locked and ref'd. If we're looking up
+ * .., dvp is unlocked. If we're looking up . an extra ref is taken, but the
+ * lock is not recursively acquired.
+ */
int
cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp,
struct timespec *tsp, int *ticksp)
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