From: Nick Piggin Date: Fri, 7 Jan 2011 06:49:33 +0000 (+1100) Subject: fs: dcache scale d_unhashed X-Git-Url: http://git.alex.org.uk fs: dcache scale d_unhashed Protect d_unhashed(dentry) condition with d_lock. This means keeping DCACHE_UNHASHED bit in synch with hash manipulations. Signed-off-by: Nick Piggin --- diff --git a/arch/powerpc/platforms/cell/spufs/inode.c b/arch/powerpc/platforms/cell/spufs/inode.c index 29a406a..5aef1a7 100644 --- a/arch/powerpc/platforms/cell/spufs/inode.c +++ b/arch/powerpc/platforms/cell/spufs/inode.c @@ -166,6 +166,9 @@ static void spufs_prune_dir(struct dentry *dir) __d_drop(dentry); spin_unlock(&dentry->d_lock); simple_unlink(dir->d_inode, dentry); + /* XXX: what is dcache_lock protecting here? Other + * filesystems (IB, configfs) release dcache_lock + * before unlink */ spin_unlock(&dcache_lock); dput(dentry); } else { diff --git a/drivers/usb/core/inode.c b/drivers/usb/core/inode.c index b690aa3..e3ab443 100644 --- a/drivers/usb/core/inode.c +++ b/drivers/usb/core/inode.c @@ -347,10 +347,13 @@ static int usbfs_empty (struct dentry *dentry) list_for_each(list, &dentry->d_subdirs) { struct dentry *de = list_entry(list, struct dentry, d_u.d_child); + spin_lock(&de->d_lock); if (usbfs_positive(de)) { + spin_unlock(&de->d_lock); spin_unlock(&dcache_lock); return 0; } + spin_unlock(&de->d_lock); } spin_unlock(&dcache_lock); diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h index 3d283ab..3912dcf 100644 --- a/fs/autofs4/autofs_i.h +++ b/fs/autofs4/autofs_i.h @@ -254,19 +254,6 @@ static inline int simple_positive(struct dentry *dentry) return dentry->d_inode && !d_unhashed(dentry); } -static inline int __simple_empty(struct dentry *dentry) -{ - struct dentry *child; - int ret = 0; - - list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child) - if (simple_positive(child)) - goto out; - ret = 1; -out: - return ret; -} - static inline void autofs4_add_expiring(struct dentry *dentry) { struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb); diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c index 413b564..ee64020 100644 --- a/fs/autofs4/expire.c +++ b/fs/autofs4/expire.c @@ -160,14 +160,18 @@ static int autofs4_tree_busy(struct vfsmount *mnt, spin_lock(&dcache_lock); for (p = top; p; p = next_dentry(p, top)) { + spin_lock(&p->d_lock); /* Negative dentry - give up */ - if (!simple_positive(p)) + if (!simple_positive(p)) { + spin_unlock(&p->d_lock); continue; + } DPRINTK("dentry %p %.*s", p, (int) p->d_name.len, p->d_name.name); - p = dget(p); + p = dget_dlock(p); + spin_unlock(&p->d_lock); spin_unlock(&dcache_lock); /* @@ -228,14 +232,18 @@ static struct dentry *autofs4_check_leaves(struct vfsmount *mnt, spin_lock(&dcache_lock); for (p = parent; p; p = next_dentry(p, parent)) { + spin_lock(&p->d_lock); /* Negative dentry - give up */ - if (!simple_positive(p)) + if (!simple_positive(p)) { + spin_unlock(&p->d_lock); continue; + } DPRINTK("dentry %p %.*s", p, (int) p->d_name.len, p->d_name.name); - p = dget(p); + p = dget_dlock(p); + spin_unlock(&p->d_lock); spin_unlock(&dcache_lock); if (d_mountpoint(p)) { @@ -324,12 +332,15 @@ struct dentry *autofs4_expire_indirect(struct super_block *sb, struct dentry *dentry = list_entry(next, struct dentry, d_u.d_child); /* Negative dentry - give up */ + spin_lock(&dentry->d_lock); if (!simple_positive(dentry)) { next = next->next; + spin_unlock(&dentry->d_lock); continue; } - dentry = dget(dentry); + dentry = dget_dlock(dentry); + spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); spin_lock(&sbi->fs_lock); diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c index 3ecf915..571f270 100644 --- a/fs/ceph/dir.c +++ b/fs/ceph/dir.c @@ -136,6 +136,7 @@ more: fi->at_end = 1; goto out_unlock; } + spin_lock(&dentry->d_lock); if (!d_unhashed(dentry) && dentry->d_inode && ceph_snap(dentry->d_inode) != CEPH_SNAPDIR && ceph_ino(dentry->d_inode) != CEPH_INO_CEPH && @@ -145,13 +146,13 @@ more: dentry->d_name.len, dentry->d_name.name, di->offset, filp->f_pos, d_unhashed(dentry) ? " unhashed" : "", !dentry->d_inode ? " null" : ""); + spin_unlock(&dentry->d_lock); p = p->prev; dentry = list_entry(p, struct dentry, d_u.d_child); di = ceph_dentry(dentry); } - spin_lock(&dentry->d_lock); - dentry->d_count++; + dget_dlock(dentry); spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); diff --git a/fs/configfs/configfs_internal.h b/fs/configfs/configfs_internal.h index da6061a..e58b4c3 100644 --- a/fs/configfs/configfs_internal.h +++ b/fs/configfs/configfs_internal.h @@ -121,6 +121,7 @@ static inline struct config_item *configfs_get_config_item(struct dentry *dentry struct config_item * item = NULL; spin_lock(&dcache_lock); + spin_lock(&dentry->d_lock); if (!d_unhashed(dentry)) { struct configfs_dirent * sd = dentry->d_fsdata; if (sd->s_type & CONFIGFS_ITEM_LINK) { @@ -129,6 +130,7 @@ static inline struct config_item *configfs_get_config_item(struct dentry *dentry } else item = config_item_get(sd->s_element); } + spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); return item; diff --git a/fs/dcache.c b/fs/dcache.c index 81e9150..ee127f9 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -46,6 +46,7 @@ * - d_name * - d_lru * - d_count + * - d_unhashed() * * Ordering: * dcache_lock @@ -53,6 +54,13 @@ * dcache_lru_lock * dcache_hash_lock * + * If there is an ancestor relationship: + * dentry->d_parent->...->d_parent->d_lock + * ... + * dentry->d_parent->d_lock + * dentry->d_lock + * + * If no ancestor relationship: * if (dentry1 < dentry2) * dentry1->d_lock * dentry2->d_lock @@ -379,7 +387,9 @@ int d_invalidate(struct dentry * dentry) * If it's already been dropped, return OK. */ spin_lock(&dcache_lock); + spin_lock(&dentry->d_lock); if (d_unhashed(dentry)) { + spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); return 0; } @@ -388,9 +398,11 @@ int d_invalidate(struct dentry * dentry) * to get rid of unused child entries. */ if (!list_empty(&dentry->d_subdirs)) { + spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); shrink_dcache_parent(dentry); spin_lock(&dcache_lock); + spin_lock(&dentry->d_lock); } /* @@ -403,7 +415,6 @@ int d_invalidate(struct dentry * dentry) * we might still populate it if it was a * working directory or similar). */ - spin_lock(&dentry->d_lock); if (dentry->d_count > 1) { if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)) { spin_unlock(&dentry->d_lock); @@ -490,35 +501,44 @@ EXPORT_SYMBOL(dget_parent); * any other hashed alias over that one unless @want_discon is set, * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias. */ - -static struct dentry * __d_find_alias(struct inode *inode, int want_discon) +static struct dentry *__d_find_alias(struct inode *inode, int want_discon) { - struct list_head *head, *next, *tmp; - struct dentry *alias, *discon_alias=NULL; + struct dentry *alias, *discon_alias; - head = &inode->i_dentry; - next = inode->i_dentry.next; - while (next != head) { - tmp = next; - next = tmp->next; - prefetch(next); - alias = list_entry(tmp, struct dentry, d_alias); +again: + discon_alias = NULL; + list_for_each_entry(alias, &inode->i_dentry, d_alias) { + spin_lock(&alias->d_lock); if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { if (IS_ROOT(alias) && - (alias->d_flags & DCACHE_DISCONNECTED)) + (alias->d_flags & DCACHE_DISCONNECTED)) { discon_alias = alias; - else if (!want_discon) { - __dget_locked(alias); + } else if (!want_discon) { + __dget_locked_dlock(alias); + spin_unlock(&alias->d_lock); + return alias; + } + } + spin_unlock(&alias->d_lock); + } + if (discon_alias) { + alias = discon_alias; + spin_lock(&alias->d_lock); + if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { + if (IS_ROOT(alias) && + (alias->d_flags & DCACHE_DISCONNECTED)) { + __dget_locked_dlock(alias); + spin_unlock(&alias->d_lock); return alias; } } + spin_unlock(&alias->d_lock); + goto again; } - if (discon_alias) - __dget_locked(discon_alias); - return discon_alias; + return NULL; } -struct dentry * d_find_alias(struct inode *inode) +struct dentry *d_find_alias(struct inode *inode) { struct dentry *de = NULL; @@ -801,8 +821,8 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry) spin_lock(&dcache_lock); spin_lock(&dentry->d_lock); dentry_lru_del(dentry); - spin_unlock(&dentry->d_lock); __d_drop(dentry); + spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); for (;;) { @@ -817,8 +837,8 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry) d_u.d_child) { spin_lock(&loop->d_lock); dentry_lru_del(loop); - spin_unlock(&loop->d_lock); __d_drop(loop); + spin_unlock(&loop->d_lock); cond_resched_lock(&dcache_lock); } spin_unlock(&dcache_lock); @@ -1863,7 +1883,10 @@ static void d_move_locked(struct dentry * dentry, struct dentry * target) /* * XXXX: do we really need to take target->d_lock? */ - if (target < dentry) { + if (d_ancestor(dentry, target)) { + spin_lock(&dentry->d_lock); + spin_lock_nested(&target->d_lock, DENTRY_D_LOCK_NESTED); + } else if (d_ancestor(target, dentry) || target < dentry) { spin_lock(&target->d_lock); spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); } else { @@ -2542,13 +2565,16 @@ resume: struct list_head *tmp = next; struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); next = tmp->next; - if (d_unhashed(dentry)||!dentry->d_inode) + spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); + if (d_unhashed(dentry) || !dentry->d_inode) { + spin_unlock(&dentry->d_lock); continue; + } if (!list_empty(&dentry->d_subdirs)) { + spin_unlock(&dentry->d_lock); this_parent = dentry; goto repeat; } - spin_lock(&dentry->d_lock); dentry->d_count--; spin_unlock(&dentry->d_lock); } diff --git a/fs/libfs.c b/fs/libfs.c index b9d25d8..433e713 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -16,6 +16,11 @@ #include +static inline int simple_positive(struct dentry *dentry) +{ + return dentry->d_inode && !d_unhashed(dentry); +} + int simple_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat) { @@ -100,8 +105,10 @@ loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin) while (n && p != &file->f_path.dentry->d_subdirs) { struct dentry *next; next = list_entry(p, struct dentry, d_u.d_child); - if (!d_unhashed(next) && next->d_inode) + spin_lock(&next->d_lock); + if (simple_positive(next)) n--; + spin_unlock(&next->d_lock); p = p->next; } list_add_tail(&cursor->d_u.d_child, p); @@ -155,9 +162,13 @@ int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir) for (p=q->next; p != &dentry->d_subdirs; p=p->next) { struct dentry *next; next = list_entry(p, struct dentry, d_u.d_child); - if (d_unhashed(next) || !next->d_inode) + spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); + if (!simple_positive(next)) { + spin_unlock(&next->d_lock); continue; + } + spin_unlock(&next->d_lock); spin_unlock(&dcache_lock); if (filldir(dirent, next->d_name.name, next->d_name.len, filp->f_pos, @@ -259,20 +270,20 @@ int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *den return 0; } -static inline int simple_positive(struct dentry *dentry) -{ - return dentry->d_inode && !d_unhashed(dentry); -} - int simple_empty(struct dentry *dentry) { struct dentry *child; int ret = 0; spin_lock(&dcache_lock); - list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child) - if (simple_positive(child)) + list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child) { + spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED); + if (simple_positive(child)) { + spin_unlock(&child->d_lock); goto out; + } + spin_unlock(&child->d_lock); + } ret = 1; out: spin_unlock(&dcache_lock); diff --git a/fs/ocfs2/dcache.c b/fs/ocfs2/dcache.c index 895532ac..35e5f5a 100644 --- a/fs/ocfs2/dcache.c +++ b/fs/ocfs2/dcache.c @@ -174,13 +174,16 @@ struct dentry *ocfs2_find_local_alias(struct inode *inode, list_for_each(p, &inode->i_dentry) { dentry = list_entry(p, struct dentry, d_alias); + spin_lock(&dentry->d_lock); if (ocfs2_match_dentry(dentry, parent_blkno, skip_unhashed)) { mlog(0, "dentry found: %.*s\n", dentry->d_name.len, dentry->d_name.name); - dget_locked(dentry); + dget_locked_dlock(dentry); + spin_unlock(&dentry->d_lock); break; } + spin_unlock(&dentry->d_lock); dentry = NULL; } diff --git a/security/tomoyo/realpath.c b/security/tomoyo/realpath.c index 1d0bf8f..d1e05b0 100644 --- a/security/tomoyo/realpath.c +++ b/security/tomoyo/realpath.c @@ -14,6 +14,7 @@ #include #include #include "common.h" +#include "../../fs/internal.h" /** * tomoyo_encode: Convert binary string to ascii string.