From fe15ce446beb3a33583af81ffe6c9d01a75314ed Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Fri, 7 Jan 2011 17:49:23 +1100 Subject: fs: change d_delete semantics 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 diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting index b12c895..9e71c9a 100644 --- a/Documentation/filesystems/porting +++ b/Documentation/filesystems/porting @@ -318,3 +318,11 @@ if it's zero is not *and* *never* *had* *been* enough. Final unlink() and iput( may happen while the inode is in the middle of ->write_inode(); e.g. if you blindly free the on-disk inode, you may end up doing that while ->write_inode() is writing to it. + +--- +[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). diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index 20899e0..95c0a93f 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -847,9 +847,9 @@ defined: 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); @@ -864,9 +864,11 @@ 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 @@ -910,14 +912,11 @@ manipulate dentries: 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 diff --git a/arch/ia64/kernel/perfmon.c b/arch/ia64/kernel/perfmon.c index 39e534f..d39d8a5 100644 --- a/arch/ia64/kernel/perfmon.c +++ b/arch/ia64/kernel/perfmon.c @@ -2185,7 +2185,7 @@ static const struct file_operations pfm_file_ops = { }; static int -pfmfs_delete_dentry(struct dentry *dentry) +pfmfs_delete_dentry(const struct dentry *dentry) { return 1; } diff --git a/drivers/staging/smbfs/dir.c b/drivers/staging/smbfs/dir.c index f088ea2..2270d48 100644 --- a/drivers/staging/smbfs/dir.c +++ b/drivers/staging/smbfs/dir.c @@ -276,7 +276,7 @@ smb_dir_open(struct inode *dir, struct file *file) static int smb_lookup_validate(struct dentry *, struct nameidata *); static int smb_hash_dentry(struct dentry *, struct qstr *); static int smb_compare_dentry(struct dentry *, struct qstr *, struct qstr *); -static int smb_delete_dentry(struct dentry *); +static int smb_delete_dentry(const struct dentry *); static const struct dentry_operations smbfs_dentry_operations = { @@ -367,7 +367,7 @@ out: * We use this to unhash dentries with bad inodes. */ static int -smb_delete_dentry(struct dentry * dentry) +smb_delete_dentry(const struct dentry *dentry) { if (dentry->d_inode) { if (is_bad_inode(dentry->d_inode)) { diff --git a/fs/9p/vfs_dentry.c b/fs/9p/vfs_dentry.c index cbf4e50..466d2a4 100644 --- a/fs/9p/vfs_dentry.c +++ b/fs/9p/vfs_dentry.c @@ -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 dentry *dentry) * */ -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, diff --git a/fs/afs/dir.c b/fs/afs/dir.c index 5439e1b..2c18cde 100644 --- a/fs/afs/dir.c +++ b/fs/afs/dir.c @@ -23,7 +23,7 @@ static struct dentry *afs_lookup(struct inode *dir, struct dentry *dentry, 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 @@ out_bad: * - 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); diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 72f31ec..7ce9f89 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -4127,7 +4127,7 @@ struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry) return inode; } -static int btrfs_dentry_delete(struct dentry *dentry) +static int btrfs_dentry_delete(const struct dentry *dentry) { struct btrfs_root *root; diff --git a/fs/coda/dir.c b/fs/coda/dir.c index 5d8b355..4cce3b07 100644 --- a/fs/coda/dir.c +++ b/fs/coda/dir.c @@ -47,7 +47,7 @@ static int coda_readdir(struct file *file, void *buf, filldir_t filldir); /* 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 @@ out: * 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; diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c index 5787069..20024a9 100644 --- a/fs/configfs/dir.c +++ b/fs/configfs/dir.c @@ -67,7 +67,7 @@ static void configfs_d_iput(struct dentry * dentry, * 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; } diff --git a/fs/dcache.c b/fs/dcache.c index b2cb266..6ee6bc4 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -453,8 +453,6 @@ static void prune_one_dentry(struct dentry * dentry) 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); diff --git a/fs/gfs2/dentry.c b/fs/gfs2/dentry.c index 6798755..e80fea2 100644 --- a/fs/gfs2/dentry.c +++ b/fs/gfs2/dentry.c @@ -106,7 +106,7 @@ static int gfs2_dhash(struct dentry *dentry, struct qstr *str) return 0; } -static int gfs2_dentry_delete(struct dentry *dentry) +static int gfs2_dentry_delete(const struct dentry *dentry) { struct gfs2_inode *ginode; diff --git a/fs/hostfs/hostfs_kern.c b/fs/hostfs/hostfs_kern.c index 2c0f148..cfe8bc7 100644 --- a/fs/hostfs/hostfs_kern.c +++ b/fs/hostfs/hostfs_kern.c @@ -32,7 +32,7 @@ static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode) #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; } diff --git a/fs/libfs.c b/fs/libfs.c index a3accdf..b9d25d8 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -37,7 +37,7 @@ int simple_statfs(struct dentry *dentry, struct kstatfs *buf) * 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; } diff --git a/fs/ncpfs/dir.c b/fs/ncpfs/dir.c index f22b12e7..d6e6453 100644 --- a/fs/ncpfs/dir.c +++ b/fs/ncpfs/dir.c @@ -76,7 +76,7 @@ const struct inode_operations ncp_dir_inode_operations = 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 = { @@ -162,7 +162,7 @@ ncp_compare_dentry(struct dentry *dentry, struct qstr *a, struct qstr *b) * 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; diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index 996dd89..9184c7c 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -1117,7 +1117,7 @@ out_error: /* * 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, diff --git a/fs/proc/base.c b/fs/proc/base.c index 1828451..d932fdb 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -1744,7 +1744,7 @@ static int pid_revalidate(struct dentry *dentry, struct nameidata *nd) 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, diff --git a/fs/proc/generic.c b/fs/proc/generic.c index dd29f03..1d607be 100644 --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -400,7 +400,7 @@ static const struct inode_operations proc_link_inode_operations = { * 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; } diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c index b652cb0..a256d77 100644 --- a/fs/proc/proc_sysctl.c +++ b/fs/proc/proc_sysctl.c @@ -392,7 +392,7 @@ static int proc_sys_revalidate(struct dentry *dentry, struct nameidata *nd) 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; } diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c index 7e54bac..27e1102 100644 --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -231,7 +231,7 @@ void release_sysfs_dirent(struct sysfs_dirent * sd) 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); diff --git a/include/linux/dcache.h b/include/linux/dcache.h index fff9755..cbfc956 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -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); diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 163c890..746055b 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2198,7 +2198,7 @@ static inline struct cftype *__file_cft(struct file *file) return __d_cft(file->f_dentry); } -static int cgroup_delete_dentry(struct dentry *dentry) +static int cgroup_delete_dentry(const struct dentry *dentry) { return 1; } diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c index 10a17a3..a0dc1a8 100644 --- a/net/sunrpc/rpc_pipe.c +++ b/net/sunrpc/rpc_pipe.c @@ -430,7 +430,7 @@ 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; } -- cgit v0.10.2