linux-fsdevel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Nick Piggin <npiggin@kernel.dk>
To: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH 10/46] hostfs: simplify locking
Date: Sat, 27 Nov 2010 20:44:40 +1100	[thread overview]
Message-ID: <00ae02ad2dc603cf4346d6d79b8960e3e9a87b50.1290852959.git.npiggin@kernel.dk> (raw)
In-Reply-To: <cover.1290852958.git.npiggin@kernel.dk>

Remove dcache_lock locking from hostfs filesystem, and move it into dcache
helpers. All that should really be required is a coherent path name, protection
from concurrent modification is not provided outside path name generation
because dcache_lock is dropped before the path is used.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
---
 fs/dcache.c             |   15 +++++++++++++--
 fs/hostfs/hostfs_kern.c |   24 ++++++++++--------------
 include/linux/dcache.h  |    2 +-
 3 files changed, 24 insertions(+), 17 deletions(-)

diff --git a/fs/dcache.c b/fs/dcache.c
index 9fd5180..4f9ccbe 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2140,7 +2140,7 @@ char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen,
 /*
  * Write full pathname from the root of the filesystem into the buffer.
  */
-char *__dentry_path(struct dentry *dentry, char *buf, int buflen)
+static char *__dentry_path(struct dentry *dentry, char *buf, int buflen)
 {
 	char *end = buf + buflen;
 	char *retval;
@@ -2167,7 +2167,18 @@ char *__dentry_path(struct dentry *dentry, char *buf, int buflen)
 Elong:
 	return ERR_PTR(-ENAMETOOLONG);
 }
-EXPORT_SYMBOL(__dentry_path);
+
+char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen)
+{
+	char *retval;
+
+	spin_lock(&dcache_lock);
+	retval = __dentry_path(dentry, buf, buflen);
+	spin_unlock(&dcache_lock);
+
+	return retval;
+}
+EXPORT_SYMBOL(dentry_path_raw);
 
 char *dentry_path(struct dentry *dentry, char *buf, int buflen)
 {
diff --git a/fs/hostfs/hostfs_kern.c b/fs/hostfs/hostfs_kern.c
index cfe8bc7..39dc505 100644
--- a/fs/hostfs/hostfs_kern.c
+++ b/fs/hostfs/hostfs_kern.c
@@ -92,12 +92,10 @@ __uml_setup("hostfs=", hostfs_args,
 
 static char *__dentry_name(struct dentry *dentry, char *name)
 {
-	char *p = __dentry_path(dentry, name, PATH_MAX);
+	char *p = dentry_path_raw(dentry, name, PATH_MAX);
 	char *root;
 	size_t len;
 
-	spin_unlock(&dcache_lock);
-
 	root = dentry->d_sb->s_fs_info;
 	len = strlen(root);
 	if (IS_ERR(p)) {
@@ -123,25 +121,23 @@ static char *dentry_name(struct dentry *dentry)
 	if (!name)
 		return NULL;
 
-	spin_lock(&dcache_lock);
 	return __dentry_name(dentry, name); /* will unlock */
 }
 
 static char *inode_name(struct inode *ino)
 {
 	struct dentry *dentry;
-	char *name = __getname();
-	if (!name)
-		return NULL;
+	char *name;
 
-	spin_lock(&dcache_lock);
-	if (list_empty(&ino->i_dentry)) {
-		spin_unlock(&dcache_lock);
-		__putname(name);
+	dentry = d_find_alias(ino);
+	if (!dentry)
 		return NULL;
-	}
-	dentry = list_first_entry(&ino->i_dentry, struct dentry, d_alias);
-	return __dentry_name(dentry, name); /* will unlock */
+
+	name = dentry_name(dentry);
+
+	dput(dentry);
+
+	return name;
 }
 
 static char *follow_link(char *link)
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 4ef2af7..6b5760b 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -309,7 +309,7 @@ extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...);
 extern char *__d_path(const struct path *path, struct path *root, char *, int);
 extern char *d_path(const struct path *, char *, int);
 extern char *d_path_with_unreachable(const struct path *, char *, int);
-extern char *__dentry_path(struct dentry *, char *, int);
+extern char *dentry_path_raw(struct dentry *, char *, int);
 extern char *dentry_path(struct dentry *, char *, int);
 
 /* Allocation counts.. */
-- 
1.7.1

  parent reply	other threads:[~2010-11-27  9:44 UTC|newest]

Thread overview: 96+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-11-27 10:15 [PATCH 00/46] rcu-walk and dcache scaling Nick Piggin
2010-11-27  9:44 ` [PATCH 02/46] fs: d_validate fixes Nick Piggin
2010-12-08  1:53   ` Dave Chinner
2010-12-08  6:59     ` Nick Piggin
2010-12-09  0:50       ` Dave Chinner
2010-12-09  4:50         ` Nick Piggin
2010-11-27  9:44 ` [PATCH 03/46] kernel: kmem_ptr_validate considered harmful Nick Piggin
2010-11-27  9:44 ` [PATCH 04/46] fs: dcache documentation cleanup Nick Piggin
2010-11-27  9:44 ` [PATCH 05/46] fs: change d_delete semantics Nick Piggin
2010-11-27  9:44 ` [PATCH 06/46] cifs: dont overwrite dentry name in d_revalidate Nick Piggin
2010-11-27  9:44 ` [PATCH 07/46] jfs: " Nick Piggin
2010-11-27  9:44 ` [PATCH 08/46] fs: change d_compare for rcu-walk Nick Piggin
2010-11-27  9:44 ` [PATCH 09/46] fs: change d_hash " Nick Piggin
2010-11-27  9:44 ` Nick Piggin [this message]
2010-11-27  9:44 ` [PATCH 11/46] fs: dcache scale hash Nick Piggin
2010-12-09  6:09   ` Dave Chinner
2010-12-09  6:28     ` Nick Piggin
2010-12-09  8:17       ` Dave Chinner
2010-12-09 12:53         ` Nick Piggin
2010-12-09 23:42           ` Dave Chinner
2010-12-10  2:35             ` Nick Piggin
2010-12-10  9:01               ` Dave Chinner
2010-12-13  4:48                 ` Nick Piggin
2010-12-13  5:05                 ` Nick Piggin
2010-11-27  9:44 ` [PATCH 12/46] fs: dcache scale lru Nick Piggin
2010-12-09  7:22   ` Dave Chinner
2010-12-09 12:34     ` Nick Piggin
2010-11-27  9:44 ` [PATCH 13/46] fs: dcache scale dentry refcount Nick Piggin
2010-11-27  9:44 ` [PATCH 14/46] fs: dcache scale d_unhashed Nick Piggin
2010-11-27  9:44 ` [PATCH 15/46] fs: dcache scale subdirs Nick Piggin
2010-11-27  9:44 ` [PATCH 16/46] fs: scale inode alias list Nick Piggin
2010-11-27  9:44 ` [PATCH 17/46] fs: Use rename lock and RCU for multi-step operations Nick Piggin
2011-01-18 22:32   ` Yehuda Sadeh Weinraub
2011-01-18 22:42     ` Nick Piggin
2011-01-19 22:27       ` Yehuda Sadeh Weinraub
2011-01-19 22:32         ` Nick Piggin
2011-01-25 22:10           ` Yehuda Sadeh Weinraub
2011-01-27  5:18             ` Nick Piggin
2011-02-07 18:52               ` Jim Schutt
2011-02-07 21:04                 ` Yehuda Sadeh Weinraub
2011-02-07 21:31                   ` Jim Schutt
2011-02-07 22:25                   ` Jim Schutt
2011-02-14 17:57               ` Yehuda Sadeh Weinraub
2010-11-27  9:44 ` [PATCH 18/46] fs: increase d_name lock coverage Nick Piggin
2010-11-27  9:44 ` [PATCH 19/46] fs: dcache remove dcache_lock Nick Piggin
2010-11-27  9:44 ` [PATCH 20/46] fs: dcache avoid starvation in dcache multi-step operations Nick Piggin
2010-11-27  9:44 ` [PATCH 21/46] fs: dcache reduce dput locking Nick Piggin
2010-11-27  9:44 ` [PATCH 22/46] fs: dcache reduce locking in d_alloc Nick Piggin
2010-11-27  9:44 ` [PATCH 23/46] fs: dcache reduce dcache_inode_lock Nick Piggin
2010-11-27  9:44 ` [PATCH 24/46] fs: dcache rationalise dget variants Nick Piggin
2010-11-27  9:44 ` [PATCH 25/46] fs: dcache reduce d_parent locking Nick Piggin
2010-11-27  9:44 ` [PATCH 26/46] fs: dcache reduce prune_one_dentry locking Nick Piggin
2010-11-27  9:44 ` [PATCH 27/46] fs: reduce dcache_inode_lock width in lru scanning Nick Piggin
2010-11-27  9:44 ` [PATCH 28/46] fs: use RCU in shrink_dentry_list to reduce lock nesting Nick Piggin
2010-11-27  9:44 ` [PATCH 29/46] fs: consolidate dentry kill sequence Nick Piggin
2010-11-27  9:45 ` [PATCH 30/46] fs: icache RCU free inodes Nick Piggin
2010-11-27  9:45 ` [PATCH 31/46] fs: avoid inode RCU freeing for pseudo fs Nick Piggin
2010-11-27  9:45 ` [PATCH 32/46] kernel: optimise seqlock Nick Piggin
2010-11-27  9:45 ` [PATCH 33/46] fs: rcu-walk for path lookup Nick Piggin
2010-11-27  9:45 ` [PATCH 34/46] fs: fs_struct use seqlock Nick Piggin
2010-11-27  9:45 ` [PATCH 35/46] fs: dcache remove d_mounted Nick Piggin
2010-11-27  9:45 ` [PATCH 36/46] fs: dcache reduce branches in lookup path Nick Piggin
2010-11-27  9:45 ` [PATCH 37/46] fs: cache optimise dentry and inode for rcu-walk Nick Piggin
2010-11-27  9:45 ` [PATCH 38/46] fs: prefetch inode data in dcache lookup Nick Piggin
2010-11-27  9:45 ` [PATCH 39/46] fs: d_revalidate_rcu for rcu-walk Nick Piggin
2010-11-27  9:45 ` [PATCH 40/46] fs: provide rcu-walk aware permission i_ops Nick Piggin
2010-11-27  9:45 ` [PATCH 41/46] fs: provide simple rcu-walk ACL implementation Nick Piggin
2010-11-27  9:45 ` [PATCH 42/46] kernel: add bl_list Nick Piggin
2010-11-27  9:45 ` [PATCH 43/46] bit_spinlock: add required includes Nick Piggin
2010-11-27  9:45 ` [PATCH 44/46] fs: dcache per-bucket dcache hash locking Nick Piggin
2010-11-27  9:45 ` [PATCH 45/46] fs: dcache per-inode inode alias locking Nick Piggin
2010-11-27  9:45 ` [PATCH 46/46] fs: improve scalability of pseudo filesystems Nick Piggin
2010-11-27  9:56 ` [PATCH 01/46] Revert "fs: use RCU read side protection in d_validate" Nick Piggin
2010-12-08  1:16   ` Dave Chinner
2010-12-08  9:38     ` Nick Piggin
2010-12-09  0:44       ` Dave Chinner
2010-12-09  4:38         ` Nick Piggin
2010-12-09  5:16           ` Nick Piggin
2010-11-27 15:04 ` [PATCH 00/46] rcu-walk and dcache scaling Anca Emanuel
2010-11-28  3:28   ` Nick Piggin
2010-11-28  6:24     ` Sedat Dilek
2010-12-01 18:03 ` David Miller
2010-12-03 16:55   ` Nick Piggin
2010-12-07 11:25 ` Dave Chinner
2010-12-07 15:24   ` Nick Piggin
2010-12-07 15:49     ` Peter Zijlstra
2010-12-07 15:59       ` Nick Piggin
2010-12-07 16:23         ` Peter Zijlstra
2010-12-08  3:28     ` Nick Piggin
2010-12-07 21:56 ` Dave Chinner
2010-12-08  1:47   ` Nick Piggin
2010-12-08  3:32     ` Dave Chinner
2010-12-08  4:28       ` Dave Chinner
2010-12-08  7:09         ` Nick Piggin
2010-12-10 20:32           ` Paul E. McKenney
2010-12-12 14:54             ` Paul E. McKenney

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=00ae02ad2dc603cf4346d6d79b8960e3e9a87b50.1290852959.git.npiggin@kernel.dk \
    --to=npiggin@kernel.dk \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).