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Message-Id: <20061114200702.12943.39624.stgit@warthog.cambridge.redhat.com>
Date: Tue, 14 Nov 2006 20:07:02 +0000
From: David Howells <dhowells@...hat.com>
To: torvalds@...l.org, akpm@...l.org, sds@...ho.nsa.gov,
trond.myklebust@....uio.no
Cc: dhowells@...hat.com, selinux@...ho.nsa.gov,
linux-kernel@...r.kernel.org, aviro@...hat.com, steved@...hat.com
Subject: [PATCH 19/19] CacheFiles: Permit daemon to probe inuseness of a cache file
Permit the daemon to probe to see whether a cache file is in use by a netfs or
not.
Signed-Off-By: David Howells <dhowells@...hat.com>
---
fs/cachefiles/cf-daemon.c | 73 +++++++++++++++++++
fs/cachefiles/cf-namei.c | 170 +++++++++++++++++++++++++++++++++++++++++++++
fs/cachefiles/internal.h | 3 +
3 files changed, 246 insertions(+), 0 deletions(-)
diff --git a/fs/cachefiles/cf-daemon.c b/fs/cachefiles/cf-daemon.c
index ae82685..ee07865 100644
--- a/fs/cachefiles/cf-daemon.c
+++ b/fs/cachefiles/cf-daemon.c
@@ -38,6 +38,7 @@ static int cachefiles_daemon_cull(struct
static int cachefiles_daemon_debug(struct cachefiles_cache *cache, char *args);
static int cachefiles_daemon_dir(struct cachefiles_cache *cache, char *args);
static int cachefiles_daemon_tag(struct cachefiles_cache *cache, char *args);
+static int cachefiles_daemon_inuse(struct cachefiles_cache *cache, char *args);
static unsigned long cachefiles_open;
@@ -66,6 +67,7 @@ static const struct cachefiles_daemon_cm
{ "frun", cachefiles_daemon_frun },
{ "fcull", cachefiles_daemon_fcull },
{ "fstop", cachefiles_daemon_fstop },
+ { "inuse", cachefiles_daemon_inuse },
{ "tag", cachefiles_daemon_tag },
{ "", NULL }
};
@@ -602,3 +604,74 @@ inval:
kerror("debug command requires mask");
return -EINVAL;
}
+
+/*
+ * find out whether an object is in use or not
+ * - command: "inuse <dirfd> <name>"
+ */
+static int cachefiles_daemon_inuse(struct cachefiles_cache *cache, char *args)
+{
+ struct dentry *dir;
+ struct file *dirfile;
+ uid_t fsuid;
+ gid_t fsgid;
+ u32 fscreatesid;
+ int dirfd, fput_needed, ret;
+
+ _enter(",%s", args);
+
+ dirfd = simple_strtoul(args, &args, 0);
+
+ if (!isspace(*args))
+ goto inval;
+
+ while (isspace(*args))
+ args++;
+
+ if (!*args)
+ goto inval;
+
+ if (strchr(args, '/'))
+ goto inval;
+
+ if (!test_bit(CACHEFILES_READY, &cache->flags)) {
+ kerror("inuse applied to unready cache");
+ return -EIO;
+ }
+
+ if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
+ kerror("inuse applied to dead cache");
+ return -EIO;
+ }
+
+ /* extract the directory dentry from the fd */
+ dirfile = fget_light(dirfd, &fput_needed);
+ if (!dirfile) {
+ kerror("cull dirfd not open");
+ return -EBADF;
+ }
+
+ dir = dget(dirfile->f_dentry);
+ fput_light(dirfile, fput_needed);
+ dirfile = NULL;
+
+ if (!S_ISDIR(dir->d_inode->i_mode))
+ goto notdir;
+
+ cachefiles_begin_secure(cache, &fsuid, &fsgid, &fscreatesid);
+ ret = cachefiles_check_in_use(cache, dir, args);
+ cachefiles_end_secure(cache, fsuid, fsgid, fscreatesid);
+
+ dput(dir);
+ _leave(" = %d", ret);
+ return ret;
+
+notdir:
+ dput(dir);
+ kerror("inuse command requires dirfd to be a directory");
+ return -ENOTDIR;
+
+inval:
+ kerror("inuse command requires dirfd and filename");
+ return -EINVAL;
+}
diff --git a/fs/cachefiles/cf-namei.c b/fs/cachefiles/cf-namei.c
index a3df94a..d0db9b3 100644
--- a/fs/cachefiles/cf-namei.c
+++ b/fs/cachefiles/cf-namei.c
@@ -524,6 +524,7 @@ nomem_d_alloc:
return ERR_PTR(-ENOMEM);
}
+#if 0
/*
* cull an object if it's not in use
* - called only by cache manager daemon
@@ -631,3 +632,172 @@ choose_error:
_leave(" = %d", ret);
return ret;
}
+#endif
+
+/*
+ * find out if an object is in use or not
+ * - if finds object and it's not in use:
+ * - returns a pointer to the object and a reference on it
+ * - returns with the directory locked
+ */
+static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
+ struct dentry *dir,
+ char *filename)
+{
+ struct cachefiles_object *object;
+ struct rb_node *_n;
+ struct dentry *victim;
+ int ret;
+
+ _enter(",%*.*s/,%s",
+ dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
+
+ /* look up the victim */
+ mutex_lock(&dir->d_inode->i_mutex);
+
+ victim = lookup_one_len(filename, dir, strlen(filename));
+ if (IS_ERR(victim))
+ goto lookup_error;
+
+ _debug("victim -> %p %s",
+ victim, victim->d_inode ? "positive" : "negative");
+
+ /* if the object is no longer there then we probably retired the object
+ * at the netfs's request whilst the cull was in progress
+ */
+ if (!victim->d_inode) {
+ mutex_unlock(&dir->d_inode->i_mutex);
+ dput(victim);
+ _leave(" = -ENOENT [absent]");
+ return ERR_PTR(-ENOENT);
+ }
+
+ /* check to see if we're using this object */
+ read_lock(&cache->active_lock);
+
+ _n = cache->active_nodes.rb_node;
+
+ while (_n) {
+ object = rb_entry(_n, struct cachefiles_object, active_node);
+
+ if (object->dentry > victim)
+ _n = _n->rb_left;
+ else if (object->dentry < victim)
+ _n = _n->rb_right;
+ else
+ goto object_in_use;
+ }
+
+ read_unlock(&cache->active_lock);
+
+ _leave(" = %p", victim);
+ return victim;
+
+object_in_use:
+ read_unlock(&cache->active_lock);
+ mutex_unlock(&dir->d_inode->i_mutex);
+ dput(victim);
+ _leave(" = -EBUSY [in use]");
+ return ERR_PTR(-EBUSY);
+
+lookup_error:
+ mutex_unlock(&dir->d_inode->i_mutex);
+ ret = PTR_ERR(victim);
+ if (ret == -ENOENT) {
+ /* file or dir now absent - probably retired by netfs */
+ _leave(" = -ESTALE [absent]");
+ return ERR_PTR(-ESTALE);
+ }
+
+ if (ret == -EIO) {
+ cachefiles_io_error(cache, "Lookup failed");
+ } else if (ret != -ENOMEM) {
+ kerror("Internal error: %d", ret);
+ ret = -EIO;
+ }
+
+ _leave(" = %d", ret);
+ return ERR_PTR(ret);
+}
+
+/*
+ * cull an object if it's not in use
+ * - called only by cache manager daemon
+ */
+int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
+ char *filename)
+{
+ struct dentry *victim;
+ int ret;
+
+ _enter(",%*.*s/,%s",
+ dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
+
+ victim = cachefiles_check_active(cache, dir, filename);
+ if (IS_ERR(victim))
+ return PTR_ERR(victim);
+
+ _debug("victim -> %p %s",
+ victim, victim->d_inode ? "positive" : "negative");
+
+ /* okay... the victim is not being used so we can cull it
+ * - start by marking it as stale
+ */
+ _debug("victim is cullable");
+
+ ret = cachefiles_remove_object_xattr(cache, victim);
+ if (ret < 0)
+ goto error_unlock;
+
+ /* actually remove the victim (drops the dir mutex) */
+ _debug("bury");
+
+ ret = cachefiles_bury_object(cache, dir, victim);
+ if (ret < 0)
+ goto error;
+
+ dput(victim);
+ _leave(" = 0");
+ return 0;
+
+error_unlock:
+ mutex_unlock(&dir->d_inode->i_mutex);
+error:
+ dput(victim);
+ if (ret == -ENOENT) {
+ /* file or dir now absent - probably retired by netfs */
+ _leave(" = -ESTALE [absent]");
+ return -ESTALE;
+ }
+
+ if (ret != -ENOMEM) {
+ kerror("Internal error: %d", ret);
+ ret = -EIO;
+ }
+
+ _leave(" = %d", ret);
+ return ret;
+}
+
+/*
+ * find out if an object is in use or not
+ * - called only by cache manager daemon
+ * - returns -EBUSY or 0 to indicate whether an object is in use or not
+ */
+int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
+ char *filename)
+{
+ struct dentry *victim;
+
+ _enter(",%*.*s/,%s",
+ dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
+
+ victim = cachefiles_check_active(cache, dir, filename);
+ if (IS_ERR(victim))
+ return PTR_ERR(victim);
+
+ mutex_unlock(&dir->d_inode->i_mutex);
+ dput(victim);
+ _leave(" = 0");
+ return 0;
+}
diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h
index d56b443..1b7ada2 100644
--- a/fs/cachefiles/internal.h
+++ b/fs/cachefiles/internal.h
@@ -183,6 +183,9 @@ extern struct dentry *cachefiles_get_dir
extern int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
char *filename);
+extern int cachefiles_check_in_use(struct cachefiles_cache *cache,
+ struct dentry *dir, char *filename);
+
/*
* cf-security.c
*/
-
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