From: Jan Blunck <jblunck@suse.de>
To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Cc: viro@zeniv.linux.org.uk, bharata@in.ibm.com, dwmw2@infradead.org,
mszeredi@suse.cz, vaurora@redhat.com
Subject: [PATCH 07/32] VFS: Introduce dput() variant that maintains a kill-list
Date: Mon, 18 May 2009 18:09:03 +0200 [thread overview]
Message-ID: <1242662968-11684-8-git-send-email-jblunck@suse.de> (raw)
In-Reply-To: <1242662968-11684-1-git-send-email-jblunck@suse.de>
This patch introduces a new variant of dput(). This becomes necessary to
prevent a recursive call to dput() from the union mount code.
void __dput(struct dentry *dentry, struct list_head *list, int greedy);
struct dentry *__d_kill(struct dentry *dentry, struct list_head *list,
int greedy);
__dput() works mostly like the original dput() did. The main difference is
that if it the greedy argument is zero it will put the parent on a special
list instead of trying to get rid of it directly.
Therefore the union mount code can safely call __dput() when it wants to get
rid of underlying dentry references during a dput(). After calling __dput()
or __d_kill() the caller must make sure that __d_kill_final() is called on all
dentries on the kill list. __d_kill_final() is actually doing the
dentry_iput() and is also dereferencing the parent.
Signed-off-by: Jan Blunck <jblunck@suse.de>
Signed-off-by: Valerie Aurora (Henson) <vaurora@redhat.com>
---
fs/dcache.c | 115 +++++++++++++++++++++++++++++++++++++++++++++++++++++-----
1 files changed, 105 insertions(+), 10 deletions(-)
diff --git a/fs/dcache.c b/fs/dcache.c
index 085f527..8bfbcd7 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -157,14 +157,19 @@ static void dentry_lru_del_init(struct dentry *dentry)
}
/**
- * d_kill - kill dentry and return parent
+ * __d_kill - kill dentry and return parent
* @dentry: dentry to kill
+ * @list: kill list
+ * @greedy: return parent instead of putting it on the kill list
*
* The dentry must already be unhashed and removed from the LRU.
*
- * If this is the root of the dentry tree, return NULL.
+ * If this is the root of the dentry tree, return NULL. If greedy is zero, we
+ * put the parent of this dentry on the kill list instead. The callers must
+ * make sure that __d_kill_final() is called on all dentries on the kill list.
*/
-static struct dentry *d_kill(struct dentry *dentry)
+static struct dentry *__d_kill(struct dentry *dentry, struct list_head *list,
+ int greedy)
__releases(dentry->d_lock)
__releases(dcache_lock)
{
@@ -172,6 +177,20 @@ static struct dentry *d_kill(struct dentry *dentry)
list_del(&dentry->d_u.d_child);
dentry_stat.nr_dentry--; /* For d_free, below */
+
+ /*
+ * If we are not greedy we just put this on a list for later processing
+ * (follow up to parent, releasing of inode and freeing dentry memory).
+ */
+ if (!greedy) {
+ list_del_init(&dentry->d_alias);
+ /* at this point nobody can reach this dentry */
+ list_add(&dentry->d_lru, list);
+ spin_unlock(&dentry->d_lock);
+ spin_unlock(&dcache_lock);
+ return NULL;
+ }
+
/*drops the locks, at that point nobody can reach this dentry */
dentry_iput(dentry);
if (IS_ROOT(dentry))
@@ -182,6 +201,54 @@ static struct dentry *d_kill(struct dentry *dentry)
return parent;
}
+void __dput(struct dentry *, struct list_head *, int);
+
+static void __d_kill_final(struct dentry *dentry, struct list_head *list)
+{
+ struct dentry *parent;
+ struct inode *inode = dentry->d_inode;
+
+ if (inode) {
+ dentry->d_inode = NULL;
+ if (!inode->i_nlink)
+ fsnotify_inoderemove(inode);
+ if (dentry->d_op && dentry->d_op->d_iput)
+ dentry->d_op->d_iput(dentry, inode);
+ else
+ iput(inode);
+ }
+
+ if (IS_ROOT(dentry))
+ parent = NULL;
+ else
+ parent = dentry->d_parent;
+ d_free(dentry);
+ __dput(parent, list, 1);
+}
+
+/**
+ * d_kill - kill dentry and return parent
+ * @dentry: dentry to kill
+ *
+ * The dentry must already be unhashed and removed from the LRU.
+ *
+ * If this is the root of the dentry tree, return NULL.
+ */
+static struct dentry *d_kill(struct dentry *dentry)
+{
+ LIST_HEAD(mortuary);
+ struct dentry *parent;
+
+ parent = __d_kill(dentry, &mortuary, 1);
+ while (!list_empty(&mortuary)) {
+ dentry = list_entry(mortuary.next, struct dentry, d_lru);
+ list_del(&dentry->d_lru);
+ __d_kill_final(dentry, &mortuary);
+ }
+
+ return parent;
+}
+
/*
* This is dput
*
@@ -199,19 +266,24 @@ static struct dentry *d_kill(struct dentry *dentry)
* Real recursion would eat up our stack space.
*/
-/*
- * dput - release a dentry
- * @dentry: dentry to release
+/**
+ * __dput - release a dentry
+ * @dentry: dentry to release
+ * @list: kill list argument for __d_kill()
+ * @greedy: greedy argument for __d_kill()
*
* Release a dentry. This will drop the usage count and if appropriate
* call the dentry unlink method as well as removing it from the queues and
* releasing its resources. If the parent dentries were scheduled for release
- * they too may now get deleted.
+ * they too may now get deleted if @greedy is not zero. Otherwise parent is
+ * added to the kill list. The callers must make sure that __d_kill_final() is
+ * called on all dentries on the kill list.
+ *
+ * You probably want to use dput() instead.
*
* no dcache lock, please.
*/
-
-void dput(struct dentry *dentry)
+void __dput(struct dentry *dentry, struct list_head *list, int greedy)
{
if (!dentry)
return;
@@ -252,12 +324,35 @@ unhash_it:
kill_it:
/* if dentry was on the d_lru list delete it from there */
dentry_lru_del(dentry);
- dentry = d_kill(dentry);
+ dentry = __d_kill(dentry, list, greedy);
if (dentry)
goto repeat;
}
/**
+ * dput - release a dentry
+ * @dentry: dentry to release
+ *
+ * Release a dentry. This will drop the usage count and if appropriate
+ * call the dentry unlink method as well as removing it from the queues and
+ * releasing its resources. If the parent dentries were scheduled for release
+ * they too may now get deleted.
+ *
+ * no dcache lock, please.
+ */
+void dput(struct dentry *dentry)
+{
+ LIST_HEAD(mortuary);
+
+ __dput(dentry, &mortuary, 1);
+ while (!list_empty(&mortuary)) {
+ dentry = list_entry(mortuary.next, struct dentry, d_lru);
+ list_del(&dentry->d_lru);
+ __d_kill_final(dentry, &mortuary);
+ }
+}
+
+/**
* d_invalidate - invalidate a dentry
* @dentry: dentry to invalidate
*
--
1.6.1.3
next prev parent reply other threads:[~2009-05-18 16:09 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-18 16:08 [PATCH 00/32] VFS based Union Mount (V3) Jan Blunck
2009-05-18 16:08 ` [PATCH 01/32] atomic: Only take lock when the counter drops to zero on UP as well Jan Blunck
2009-05-18 16:08 ` [PATCH 02/32] VFS: BUG() if somebody tries to rehash an already hashed dentry Jan Blunck
2009-05-18 16:08 ` [PATCH 03/32] VFS: propagate mnt_flags into do_loopback Jan Blunck
2009-05-18 16:09 ` [PATCH 04/32] VFS: Make lookup_hash() return a struct path Jan Blunck
2009-05-18 16:09 ` [PATCH 05/32] VFS: Remove unnecessary micro-optimization in cached_lookup() Jan Blunck
2009-05-18 16:09 ` [PATCH 06/32] VFS: Make real_lookup() return a struct path Jan Blunck
2009-05-18 16:09 ` Jan Blunck [this message]
2009-05-18 16:09 ` [PATCH 08/32] whiteout: Don't return information about whiteouts to userspace Jan Blunck
2009-05-18 16:09 ` [PATCH 09/32] whiteout: Add vfs_whiteout() and whiteout inode operation Jan Blunck
2009-05-18 16:09 ` [PATCH 10/32] whiteout: Set S_OPAQUE inode flag when creating directories Jan Blunck
2009-05-18 16:09 ` [PATCH 11/32] whiteout: Add whiteout support to tmpfs Jan Blunck
2009-05-18 16:09 ` [PATCH 12/32] whiteout: Split of ext2_append_link() from ext2_add_link() Jan Blunck
2009-05-18 16:09 ` [PATCH 13/32] whiteout: Add whiteout support to ext2 Jan Blunck
2009-05-18 16:09 ` [PATCH 14/32] whiteout: Add path_whiteout() helper Jan Blunck
2009-05-18 16:09 ` [PATCH 15/32] union-mount: Documentation Jan Blunck
2009-05-25 6:25 ` hooanon05
2009-05-25 8:03 ` Arnd Bergmann
2009-05-25 8:43 ` hooanon05
2009-06-18 19:05 ` Valerie Aurora
2009-06-19 1:53 ` hooanon05
2009-05-18 16:09 ` [PATCH 16/32] union-mount: Introduce MNT_UNION and MS_UNION flags Jan Blunck
2009-05-18 16:09 ` [PATCH 17/32] union-mount: Introduce union_mount structure Jan Blunck
2009-05-18 16:09 ` [PATCH 18/32] union-mount: Drive the union cache via dcache Jan Blunck
2009-05-18 16:09 ` [PATCH 19/32] union-mount: Some checks during namespace changes Jan Blunck
2009-05-18 16:09 ` [PATCH 20/32] union-mount: Changes to the namespace handling Jan Blunck
2009-05-18 16:09 ` [PATCH 21/32] union-mount: Make lookup work for union-mounted file systems Jan Blunck
2009-05-19 16:15 ` Miklos Szeredi
2009-05-19 17:30 ` Valerie Aurora
2009-05-20 10:21 ` Miklos Szeredi
2009-05-18 16:09 ` [PATCH 22/32] union-mount: stop lookup when directory has S_OPAQUE flag set Jan Blunck
2009-05-18 16:09 ` [PATCH 23/32] union-mount: stop lookup when finding a whiteout Jan Blunck
2009-05-18 16:09 ` [PATCH 24/32] union-mount: in-kernel file copy between union mounted filesystems Jan Blunck
2009-05-18 16:09 ` [PATCH 25/32] union-mount: check for logically empty directory (FIXME) Jan Blunck
2009-05-18 16:09 ` [PATCH 26/32] union-mount: call do_whiteout() on unlink and rmdir Jan Blunck
2009-05-18 16:09 ` [PATCH 27/32] union-mount: Always create topmost directory on open Jan Blunck
2009-05-18 16:09 ` [PATCH 28/32] union-mount: Basic fallthru definitions Jan Blunck
2009-05-18 16:09 ` [PATCH 29/32] union mount: Support for fallthru entries in union mount lookup Jan Blunck
2009-05-18 16:09 ` [PATCH 30/32] union mount: ext2 fallthru support Jan Blunck
2009-05-18 16:32 ` Andreas Dilger
2009-05-19 9:42 ` Jan Blunck
2009-05-19 14:05 ` Andreas Dilger
2009-05-19 16:13 ` Jan Blunck
2009-05-18 16:09 ` [PATCH 31/32] union-mount: tmpfs " Jan Blunck
2009-05-18 16:09 ` [PATCH 32/32] union-mount: Copy up directory entries on first readdir() Jan Blunck
2009-05-18 20:40 ` [PATCH] Userland for VFS based Union Mount (V3) Valerie Aurora
2009-05-21 13:53 ` Andreas Dilger
2009-06-18 3:22 ` Valerie Aurora
2009-05-19 9:48 ` [PATCH 00/32] " Miklos Szeredi
2009-05-19 10:29 ` Jan Blunck
2009-05-19 10:35 ` Miklos Szeredi
2009-05-19 10:39 ` Jan Blunck
2009-05-19 11:54 ` Arnd Bergmann
2009-05-19 12:15 ` Jan Blunck
2009-05-19 12:21 ` Arnd Bergmann
2009-05-19 13:10 ` Jan Blunck
2009-05-19 17:23 ` Valerie Aurora
2009-05-20 9:05 ` Miklos Szeredi
2009-06-08 19:44 ` Valerie Aurora
2009-06-16 15:19 ` Miklos Szeredi
2009-05-21 12:54 ` Jan Rekorajski
2009-06-08 19:57 ` Valerie Aurora
2009-06-08 22:44 ` Jan Rekorajski
2009-06-08 22:48 ` Valerie Aurora
2009-06-15 9:55 ` Jan Rekorajski
2009-06-18 3:23 ` Valerie Aurora
2009-06-04 11:38 ` Scott James Remnant
2009-06-09 22:15 ` Valerie Aurora
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