From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752153Ab0KINBm (ORCPT ); Tue, 9 Nov 2010 08:01:42 -0500 Received: from ipmail06.adl2.internode.on.net ([150.101.137.129]:3844 "EHLO ipmail06.adl2.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751202Ab0KINBi (ORCPT ); Tue, 9 Nov 2010 08:01:38 -0500 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AvsEAHDU2Ex5LcZK/2dsb2JhbACiH3K/QYVKBIUQilQ Date: Wed, 10 Nov 2010 00:01:33 +1100 From: Nick Piggin To: Al Viro , Linus Torvalds Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: [patch 4/6] fs: d_delete change Message-ID: <20101109130133.GE11477@amd> References: <20101109124610.GB11477@amd> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20101109124610.GB11477@amd> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Actually this change is required for basic dcache scaling rather than rcu-walk, but I think it's a good one anyway. Should be easy to merge. -- Change d_delete from a dentry deletion notification to a dentry caching advise, more like ->drop_inode. Require it to be constant and idempotent, and not take d_lock. This is how all existing filesystems use the callback anyway. This makes fine grained dentry locking of dput and dentry lru scanning much simpler. Signed-off-by: Nick Piggin --- Documentation/filesystems/porting | 7 +++++++ Documentation/filesystems/vfs.txt | 27 +++++++++++++-------------- arch/ia64/kernel/perfmon.c | 2 +- fs/9p/vfs_dentry.c | 4 ++-- fs/afs/dir.c | 4 ++-- fs/btrfs/inode.c | 2 +- fs/coda/dir.c | 4 ++-- fs/configfs/dir.c | 2 +- fs/dcache.c | 2 -- fs/gfs2/dentry.c | 2 +- fs/hostfs/hostfs_kern.c | 2 +- fs/libfs.c | 2 +- fs/ncpfs/dir.c | 4 ++-- fs/nfs/dir.c | 2 +- fs/proc/base.c | 2 +- fs/proc/generic.c | 2 +- fs/proc/proc_sysctl.c | 2 +- fs/sysfs/dir.c | 2 +- include/linux/dcache.h | 6 +++--- net/sunrpc/rpc_pipe.c | 2 +- 20 files changed, 43 insertions(+), 39 deletions(-) Index: linux-2.6/Documentation/filesystems/porting =================================================================== --- linux-2.6.orig/Documentation/filesystems/porting 2010-11-09 22:11:10.000000000 +1100 +++ linux-2.6/Documentation/filesystems/porting 2010-11-09 23:22:51.000000000 +1100 @@ -330,3 +330,10 @@ namespace). to be reinitialized before it is freed, so INIT_LIST_HEAD(&inode->i_dentry) must be done in the RCU callback. +--- +[mandatory] + + .d_delete() now only advises the dcache as to whether or not to cache +unreferenced dentries, and is now only called when the dentry refcount goes to +0. Even on 0 refcount transition, it must be able to tolerate being called 0, 1, +or more times (eg. constant, idempotent). Index: linux-2.6/Documentation/filesystems/vfs.txt =================================================================== --- linux-2.6.orig/Documentation/filesystems/vfs.txt 2010-11-09 22:10:59.000000000 +1100 +++ linux-2.6/Documentation/filesystems/vfs.txt 2010-11-09 23:22:51.000000000 +1100 @@ -841,9 +841,9 @@ the VFS uses a default. As of kernel 2.6 struct dentry_operations { int (*d_revalidate)(struct dentry *, struct nameidata *); - int (*d_hash) (struct dentry *, struct qstr *); - int (*d_compare) (struct dentry *, struct qstr *, struct qstr *); - int (*d_delete)(struct dentry *); + int (*d_hash)(struct dentry *, struct qstr *); + int (*d_compare)(struct dentry *, struct qstr *, struct qstr *); + int (*d_delete)(const struct dentry *); void (*d_release)(struct dentry *); void (*d_iput)(struct dentry *, struct inode *); char *(*d_dname)(struct dentry *, char *, int); @@ -858,9 +858,11 @@ struct dentry_operations { d_compare: called when a dentry should be compared with another - d_delete: called when the last reference to a dentry is - deleted. This means no-one is using the dentry, however it is - still valid and in the dcache + d_delete: called when the last reference to a dentry is dropped and the + dcache is deciding whether or not to cache it. Return 1 to delete + immediately, or 0 to cache the dentry. Default is NULL which means to + always cache a reachable dentry. d_delete must be constant and + idempotent. d_release: called when a dentry is really deallocated @@ -904,14 +906,11 @@ There are a number of functions defined the usage count) dput: close a handle for a dentry (decrements the usage count). If - the usage count drops to 0, the "d_delete" method is called - and the dentry is placed on the unused list if the dentry is - still in its parents hash list. Putting the dentry on the - unused list just means that if the system needs some RAM, it - goes through the unused list of dentries and deallocates them. - If the dentry has already been unhashed and the usage count - drops to 0, in this case the dentry is deallocated after the - "d_delete" method is called + the usage count drops to 0, and the dentry is still in its + parent's hash, the "d_delete" method is called to check whether + it should be cached. If it should not be cached, or if the dentry + is not hashed, it is deleted. Otherwise cached dentries are put + into an LRU list to be reclaimed on memory shortage. d_drop: this unhashes a dentry from its parents hash list. A subsequent call to dput() will deallocate the dentry if its Index: linux-2.6/fs/dcache.c =================================================================== --- linux-2.6.orig/fs/dcache.c 2010-11-09 22:10:59.000000000 +1100 +++ linux-2.6/fs/dcache.c 2010-11-09 23:22:51.000000000 +1100 @@ -446,8 +446,6 @@ static void prune_one_dentry(struct dent if (!atomic_dec_and_lock(&dentry->d_count, &dentry->d_lock)) return; - if (dentry->d_op && dentry->d_op->d_delete) - dentry->d_op->d_delete(dentry); dentry_lru_del(dentry); __d_drop(dentry); dentry = d_kill(dentry); Index: linux-2.6/include/linux/dcache.h =================================================================== --- linux-2.6.orig/include/linux/dcache.h 2010-11-09 22:11:10.000000000 +1100 +++ linux-2.6/include/linux/dcache.h 2010-11-09 23:22:51.000000000 +1100 @@ -133,9 +133,9 @@ enum dentry_d_lock_class struct dentry_operations { int (*d_revalidate)(struct dentry *, struct nameidata *); - int (*d_hash) (struct dentry *, struct qstr *); - int (*d_compare) (struct dentry *, struct qstr *, struct qstr *); - int (*d_delete)(struct dentry *); + int (*d_hash)(struct dentry *, struct qstr *); + int (*d_compare)(struct dentry *, struct qstr *, struct qstr *); + int (*d_delete)(const struct dentry *); void (*d_release)(struct dentry *); void (*d_iput)(struct dentry *, struct inode *); char *(*d_dname)(struct dentry *, char *, int); Index: linux-2.6/arch/ia64/kernel/perfmon.c =================================================================== --- linux-2.6.orig/arch/ia64/kernel/perfmon.c 2010-11-09 22:10:59.000000000 +1100 +++ linux-2.6/arch/ia64/kernel/perfmon.c 2010-11-09 22:11:10.000000000 +1100 @@ -2185,7 +2185,7 @@ static const struct file_operations pfm_ }; static int -pfmfs_delete_dentry(struct dentry *dentry) +pfmfs_delete_dentry(const struct dentry *dentry) { return 1; } Index: linux-2.6/fs/9p/vfs_dentry.c =================================================================== --- linux-2.6.orig/fs/9p/vfs_dentry.c 2010-11-09 22:10:59.000000000 +1100 +++ linux-2.6/fs/9p/vfs_dentry.c 2010-11-09 22:11:10.000000000 +1100 @@ -51,7 +51,7 @@ * */ -static int v9fs_dentry_delete(struct dentry *dentry) +static int v9fs_dentry_delete(const struct dentry *dentry) { P9_DPRINTK(P9_DEBUG_VFS, " dentry: %s (%p)\n", dentry->d_name.name, dentry); @@ -68,7 +68,7 @@ static int v9fs_dentry_delete(struct den * */ -static int v9fs_cached_dentry_delete(struct dentry *dentry) +static int v9fs_cached_dentry_delete(const struct dentry *dentry) { struct inode *inode = dentry->d_inode; P9_DPRINTK(P9_DEBUG_VFS, " dentry: %s (%p)\n", dentry->d_name.name, Index: linux-2.6/fs/afs/dir.c =================================================================== --- linux-2.6.orig/fs/afs/dir.c 2010-11-09 22:11:00.000000000 +1100 +++ linux-2.6/fs/afs/dir.c 2010-11-09 22:11:10.000000000 +1100 @@ -23,7 +23,7 @@ static struct dentry *afs_lookup(struct static int afs_dir_open(struct inode *inode, struct file *file); static int afs_readdir(struct file *file, void *dirent, filldir_t filldir); static int afs_d_revalidate(struct dentry *dentry, struct nameidata *nd); -static int afs_d_delete(struct dentry *dentry); +static int afs_d_delete(const struct dentry *dentry); static void afs_d_release(struct dentry *dentry); static int afs_lookup_filldir(void *_cookie, const char *name, int nlen, loff_t fpos, u64 ino, unsigned dtype); @@ -730,7 +730,7 @@ static int afs_d_revalidate(struct dentr * - called from dput() when d_count is going to 0. * - return 1 to request dentry be unhashed, 0 otherwise */ -static int afs_d_delete(struct dentry *dentry) +static int afs_d_delete(const struct dentry *dentry) { _enter("%s", dentry->d_name.name); Index: linux-2.6/fs/btrfs/inode.c =================================================================== --- linux-2.6.orig/fs/btrfs/inode.c 2010-11-09 22:11:10.000000000 +1100 +++ linux-2.6/fs/btrfs/inode.c 2010-11-09 22:11:10.000000000 +1100 @@ -4127,7 +4127,7 @@ struct inode *btrfs_lookup_dentry(struct return inode; } -static int btrfs_dentry_delete(struct dentry *dentry) +static int btrfs_dentry_delete(const struct dentry *dentry) { struct btrfs_root *root; Index: linux-2.6/fs/coda/dir.c =================================================================== --- linux-2.6.orig/fs/coda/dir.c 2010-11-09 22:10:59.000000000 +1100 +++ linux-2.6/fs/coda/dir.c 2010-11-09 22:11:10.000000000 +1100 @@ -47,7 +47,7 @@ static int coda_readdir(struct file *fil /* dentry ops */ static int coda_dentry_revalidate(struct dentry *de, struct nameidata *nd); -static int coda_dentry_delete(struct dentry *); +static int coda_dentry_delete(const struct dentry *); /* support routines */ static int coda_venus_readdir(struct file *coda_file, void *buf, @@ -577,7 +577,7 @@ static int coda_dentry_revalidate(struct * This is the callback from dput() when d_count is going to 0. * We use this to unhash dentries with bad inodes. */ -static int coda_dentry_delete(struct dentry * dentry) +static int coda_dentry_delete(const struct dentry * dentry) { int flags; Index: linux-2.6/fs/configfs/dir.c =================================================================== --- linux-2.6.orig/fs/configfs/dir.c 2010-11-09 22:10:59.000000000 +1100 +++ linux-2.6/fs/configfs/dir.c 2010-11-09 22:11:10.000000000 +1100 @@ -67,7 +67,7 @@ static void configfs_d_iput(struct dentr * We _must_ delete our dentries on last dput, as the chain-to-parent * behavior is required to clear the parents of default_groups. */ -static int configfs_d_delete(struct dentry *dentry) +static int configfs_d_delete(const struct dentry *dentry) { return 1; } Index: linux-2.6/fs/gfs2/dentry.c =================================================================== --- linux-2.6.orig/fs/gfs2/dentry.c 2010-11-09 22:11:00.000000000 +1100 +++ linux-2.6/fs/gfs2/dentry.c 2010-11-09 23:22:50.000000000 +1100 @@ -106,7 +106,7 @@ static int gfs2_dhash(struct dentry *den return 0; } -static int gfs2_dentry_delete(struct dentry *dentry) +static int gfs2_dentry_delete(const struct dentry *dentry) { struct gfs2_inode *ginode; Index: linux-2.6/fs/hostfs/hostfs_kern.c =================================================================== --- linux-2.6.orig/fs/hostfs/hostfs_kern.c 2010-11-09 22:11:10.000000000 +1100 +++ linux-2.6/fs/hostfs/hostfs_kern.c 2010-11-09 22:11:10.000000000 +1100 @@ -32,7 +32,7 @@ static inline struct hostfs_inode_info * #define FILE_HOSTFS_I(file) HOSTFS_I((file)->f_path.dentry->d_inode) -static int hostfs_d_delete(struct dentry *dentry) +static int hostfs_d_delete(const struct dentry *dentry) { return 1; } Index: linux-2.6/fs/libfs.c =================================================================== --- linux-2.6.orig/fs/libfs.c 2010-11-09 22:10:59.000000000 +1100 +++ linux-2.6/fs/libfs.c 2010-11-09 22:11:10.000000000 +1100 @@ -37,7 +37,7 @@ int simple_statfs(struct dentry *dentry, * Retaining negative dentries for an in-memory filesystem just wastes * memory and lookup time: arrange for them to be deleted immediately. */ -static int simple_delete_dentry(struct dentry *dentry) +static int simple_delete_dentry(const struct dentry *dentry) { return 1; } Index: linux-2.6/fs/ncpfs/dir.c =================================================================== --- linux-2.6.orig/fs/ncpfs/dir.c 2010-11-09 22:10:59.000000000 +1100 +++ linux-2.6/fs/ncpfs/dir.c 2010-11-09 23:22:51.000000000 +1100 @@ -77,7 +77,7 @@ const struct inode_operations ncp_dir_in static int ncp_lookup_validate(struct dentry *, struct nameidata *); static int ncp_hash_dentry(struct dentry *, struct qstr *); static int ncp_compare_dentry (struct dentry *, struct qstr *, struct qstr *); -static int ncp_delete_dentry(struct dentry *); +static int ncp_delete_dentry(const struct dentry *); static const struct dentry_operations ncp_dentry_operations = { @@ -163,7 +163,7 @@ ncp_compare_dentry(struct dentry *dentry * Closing files can be safely postponed until iput() - it's done there anyway. */ static int -ncp_delete_dentry(struct dentry * dentry) +ncp_delete_dentry(const struct dentry * dentry) { struct inode *inode = dentry->d_inode; Index: linux-2.6/fs/nfs/dir.c =================================================================== --- linux-2.6.orig/fs/nfs/dir.c 2010-11-09 22:10:59.000000000 +1100 +++ linux-2.6/fs/nfs/dir.c 2010-11-09 22:11:10.000000000 +1100 @@ -1091,7 +1091,7 @@ static int nfs_lookup_revalidate(struct /* * This is called from dput() when d_count is going to 0. */ -static int nfs_dentry_delete(struct dentry *dentry) +static int nfs_dentry_delete(const struct dentry *dentry) { dfprintk(VFS, "NFS: dentry_delete(%s/%s, %x)\n", dentry->d_parent->d_name.name, dentry->d_name.name, Index: linux-2.6/fs/proc/base.c =================================================================== --- linux-2.6.orig/fs/proc/base.c 2010-11-09 22:10:59.000000000 +1100 +++ linux-2.6/fs/proc/base.c 2010-11-09 22:11:10.000000000 +1100 @@ -1744,7 +1744,7 @@ static int pid_revalidate(struct dentry return 0; } -static int pid_delete_dentry(struct dentry * dentry) +static int pid_delete_dentry(const struct dentry * dentry) { /* Is the task we represent dead? * If so, then don't put the dentry on the lru list, Index: linux-2.6/fs/proc/generic.c =================================================================== --- linux-2.6.orig/fs/proc/generic.c 2010-11-09 22:10:59.000000000 +1100 +++ linux-2.6/fs/proc/generic.c 2010-11-09 22:11:10.000000000 +1100 @@ -400,7 +400,7 @@ static const struct inode_operations pro * smarter: we could keep a "volatile" flag in the * inode to indicate which ones to keep. */ -static int proc_delete_dentry(struct dentry * dentry) +static int proc_delete_dentry(const struct dentry * dentry) { return 1; } Index: linux-2.6/fs/proc/proc_sysctl.c =================================================================== --- linux-2.6.orig/fs/proc/proc_sysctl.c 2010-11-09 22:10:59.000000000 +1100 +++ linux-2.6/fs/proc/proc_sysctl.c 2010-11-09 23:22:51.000000000 +1100 @@ -392,7 +392,7 @@ static int proc_sys_revalidate(struct de return !PROC_I(dentry->d_inode)->sysctl->unregistering; } -static int proc_sys_delete(struct dentry *dentry) +static int proc_sys_delete(const struct dentry *dentry) { return !!PROC_I(dentry->d_inode)->sysctl->unregistering; } Index: linux-2.6/fs/sysfs/dir.c =================================================================== --- linux-2.6.orig/fs/sysfs/dir.c 2010-11-09 22:10:59.000000000 +1100 +++ linux-2.6/fs/sysfs/dir.c 2010-11-09 22:11:10.000000000 +1100 @@ -231,7 +231,7 @@ void release_sysfs_dirent(struct sysfs_d goto repeat; } -static int sysfs_dentry_delete(struct dentry *dentry) +static int sysfs_dentry_delete(const struct dentry *dentry) { struct sysfs_dirent *sd = dentry->d_fsdata; return !!(sd->s_flags & SYSFS_FLAG_REMOVED); Index: linux-2.6/net/sunrpc/rpc_pipe.c =================================================================== --- linux-2.6.orig/net/sunrpc/rpc_pipe.c 2010-11-09 22:11:10.000000000 +1100 +++ linux-2.6/net/sunrpc/rpc_pipe.c 2010-11-09 22:11:10.000000000 +1100 @@ -438,7 +438,7 @@ void rpc_put_mount(void) } EXPORT_SYMBOL_GPL(rpc_put_mount); -static int rpc_delete_dentry(struct dentry *dentry) +static int rpc_delete_dentry(const struct dentry *dentry) { return 1; }