diff options
Diffstat (limited to 'fs/dcache.c')
| -rw-r--r-- | fs/dcache.c | 375 |
1 files changed, 207 insertions, 168 deletions
diff --git a/fs/dcache.c b/fs/dcache.c index 41000305d71..a9dd384c5e8 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -343,6 +343,7 @@ static void dentry_unlink_inode(struct dentry * dentry) __releases(dentry->d_inode->i_lock) { struct inode *inode = dentry->d_inode; + __d_clear_type(dentry); dentry->d_inode = NULL; hlist_del_init(&dentry->d_alias); dentry_rcuwalk_barrier(dentry); @@ -483,27 +484,6 @@ static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent) return parent; } -/* - * Unhash a dentry without inserting an RCU walk barrier or checking that - * dentry->d_lock is locked. The caller must take care of that, if - * appropriate. - */ -static void __d_shrink(struct dentry *dentry) -{ - if (!d_unhashed(dentry)) { - struct hlist_bl_head *b; - if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED)) - b = &dentry->d_sb->s_anon; - else - b = d_hash(dentry->d_parent, dentry->d_name.hash); - - hlist_bl_lock(b); - __hlist_bl_del(&dentry->d_hash); - dentry->d_hash.pprev = NULL; - hlist_bl_unlock(b); - } -} - /** * d_drop - drop a dentry * @dentry: dentry to drop @@ -522,7 +502,21 @@ static void __d_shrink(struct dentry *dentry) void __d_drop(struct dentry *dentry) { if (!d_unhashed(dentry)) { - __d_shrink(dentry); + struct hlist_bl_head *b; + /* + * Hashed dentries are normally on the dentry hashtable, + * with the exception of those newly allocated by + * d_obtain_alias, which are always IS_ROOT: + */ + if (unlikely(IS_ROOT(dentry))) + b = &dentry->d_sb->s_anon; + else + b = d_hash(dentry->d_parent, dentry->d_name.hash); + + hlist_bl_lock(b); + __hlist_bl_del(&dentry->d_hash); + dentry->d_hash.pprev = NULL; + hlist_bl_unlock(b); dentry_rcuwalk_barrier(dentry); } } @@ -542,7 +536,7 @@ EXPORT_SYMBOL(d_drop); * If ref is non-zero, then decrement the refcount too. * Returns dentry requiring refcount drop, or NULL if we're done. */ -static inline struct dentry * +static struct dentry * dentry_kill(struct dentry *dentry, int unlock_on_failure) __releases(dentry->d_lock) { @@ -630,7 +624,8 @@ repeat: goto kill_it; } - dentry->d_flags |= DCACHE_REFERENCED; + if (!(dentry->d_flags & DCACHE_REFERENCED)) + dentry->d_flags |= DCACHE_REFERENCED; dentry_lru_add(dentry); dentry->d_lockref.count--; @@ -1075,116 +1070,6 @@ void shrink_dcache_sb(struct super_block *sb) EXPORT_SYMBOL(shrink_dcache_sb); /* - * destroy a single subtree of dentries for unmount - * - see the comments on shrink_dcache_for_umount() for a description of the - * locking - */ -static void shrink_dcache_for_umount_subtree(struct dentry *dentry) -{ - struct dentry *parent; - - BUG_ON(!IS_ROOT(dentry)); - - for (;;) { - /* descend to the first leaf in the current subtree */ - while (!list_empty(&dentry->d_subdirs)) - dentry = list_entry(dentry->d_subdirs.next, - struct dentry, d_u.d_child); - - /* consume the dentries from this leaf up through its parents - * until we find one with children or run out altogether */ - do { - struct inode *inode; - - /* - * inform the fs that this dentry is about to be - * unhashed and destroyed. - */ - if ((dentry->d_flags & DCACHE_OP_PRUNE) && - !d_unhashed(dentry)) - dentry->d_op->d_prune(dentry); - - dentry_lru_del(dentry); - __d_shrink(dentry); - - if (dentry->d_lockref.count != 0) { - printk(KERN_ERR - "BUG: Dentry %p{i=%lx,n=%s}" - " still in use (%d)" - " [unmount of %s %s]\n", - dentry, - dentry->d_inode ? - dentry->d_inode->i_ino : 0UL, - dentry->d_name.name, - dentry->d_lockref.count, - dentry->d_sb->s_type->name, - dentry->d_sb->s_id); - BUG(); - } - - if (IS_ROOT(dentry)) { - parent = NULL; - list_del(&dentry->d_u.d_child); - } else { - parent = dentry->d_parent; - parent->d_lockref.count--; - list_del(&dentry->d_u.d_child); - } - - inode = dentry->d_inode; - if (inode) { - dentry->d_inode = NULL; - hlist_del_init(&dentry->d_alias); - if (dentry->d_op && dentry->d_op->d_iput) - dentry->d_op->d_iput(dentry, inode); - else - iput(inode); - } - - d_free(dentry); - - /* finished when we fall off the top of the tree, - * otherwise we ascend to the parent and move to the - * next sibling if there is one */ - if (!parent) - return; - dentry = parent; - } while (list_empty(&dentry->d_subdirs)); - - dentry = list_entry(dentry->d_subdirs.next, - struct dentry, d_u.d_child); - } -} - -/* - * destroy the dentries attached to a superblock on unmounting - * - we don't need to use dentry->d_lock because: - * - the superblock is detached from all mountings and open files, so the - * dentry trees will not be rearranged by the VFS - * - s_umount is write-locked, so the memory pressure shrinker will ignore - * any dentries belonging to this superblock that it comes across - * - the filesystem itself is no longer permitted to rearrange the dentries - * in this superblock - */ -void shrink_dcache_for_umount(struct super_block *sb) -{ - struct dentry *dentry; - - if (down_read_trylock(&sb->s_umount)) - BUG(); - - dentry = sb->s_root; - sb->s_root = NULL; - dentry->d_lockref.count--; - shrink_dcache_for_umount_subtree(dentry); - - while (!hlist_bl_empty(&sb->s_anon)) { - dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash); - shrink_dcache_for_umount_subtree(dentry); - } -} - -/* * This tries to ascend one level of parenthood, but * we can race with renaming, so we need to re-check * the parenthood after dropping the lock and check @@ -1331,14 +1216,6 @@ rename_retry: * list is non-empty and continue searching. */ -/** - * have_submounts - check for mounts over a dentry - * @parent: dentry to check. - * - * Return true if the parent or its subdirectories contain - * a mount point - */ - static enum d_walk_ret check_mount(void *data, struct dentry *dentry) { int *ret = data; @@ -1349,6 +1226,13 @@ static enum d_walk_ret check_mount(void *data, struct dentry *dentry) return D_WALK_CONTINUE; } +/** + * have_submounts - check for mounts over a dentry + * @parent: dentry to check. + * + * Return true if the parent or its subdirectories contain + * a mount point + */ int have_submounts(struct dentry *parent) { int ret = 0; @@ -1478,6 +1362,91 @@ void shrink_dcache_parent(struct dentry *parent) } EXPORT_SYMBOL(shrink_dcache_parent); +static enum d_walk_ret umount_collect(void *_data, struct dentry *dentry) +{ + struct select_data *data = _data; + enum d_walk_ret ret = D_WALK_CONTINUE; + + if (dentry->d_lockref.count) { + dentry_lru_del(dentry); + if (likely(!list_empty(&dentry->d_subdirs))) + goto out; + if (dentry == data->start && dentry->d_lockref.count == 1) + goto out; + printk(KERN_ERR + "BUG: Dentry %p{i=%lx,n=%s}" + " still in use (%d)" + " [unmount of %s %s]\n", + dentry, + dentry->d_inode ? + dentry->d_inode->i_ino : 0UL, + dentry->d_name.name, + dentry->d_lockref.count, + dentry->d_sb->s_type->name, + dentry->d_sb->s_id); + BUG(); + } else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) { + /* + * We can't use d_lru_shrink_move() because we + * need to get the global LRU lock and do the + * LRU accounting. + */ + if (dentry->d_flags & DCACHE_LRU_LIST) + d_lru_del(dentry); + d_shrink_add(dentry, &data->dispose); + data->found++; + ret = D_WALK_NORETRY; + } +out: + if (data->found && need_resched()) + ret = D_WALK_QUIT; + return ret; +} + +/* + * destroy the dentries attached to a superblock on unmounting + */ +void shrink_dcache_for_umount(struct super_block *sb) +{ + struct dentry *dentry; + + if (down_read_trylock(&sb->s_umount)) + BUG(); + + dentry = sb->s_root; + sb->s_root = NULL; + for (;;) { + struct select_data data; + + INIT_LIST_HEAD(&data.dispose); + data.start = dentry; + data.found = 0; + + d_walk(dentry, &data, umount_collect, NULL); + if (!data.found) + break; + + shrink_dentry_list(&data.dispose); + cond_resched(); + } + d_drop(dentry); + dput(dentry); + + while (!hlist_bl_empty(&sb->s_anon)) { + struct select_data data; + dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash); + + INIT_LIST_HEAD(&data.dispose); + data.start = NULL; + data.found = 0; + + d_walk(dentry, &data, umount_collect, NULL); + if (data.found) + shrink_dentry_list(&data.dispose); + cond_resched(); + } +} + static enum d_walk_ret check_and_collect(void *_data, struct dentry *dentry) { struct select_data *data = _data; @@ -1638,12 +1607,17 @@ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) } EXPORT_SYMBOL(d_alloc); +/** + * d_alloc_pseudo - allocate a dentry (for lookup-less filesystems) + * @sb: the superblock + * @name: qstr of the name + * + * For a filesystem that just pins its dentries in memory and never + * performs lookups at all, return an unhashed IS_ROOT dentry. + */ struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name) { - struct dentry *dentry = __d_alloc(sb, name); - if (dentry) - dentry->d_flags |= DCACHE_DISCONNECTED; - return dentry; + return __d_alloc(sb, name); } EXPORT_SYMBOL(d_alloc_pseudo); @@ -1685,14 +1659,42 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) } EXPORT_SYMBOL(d_set_d_op); +static unsigned d_flags_for_inode(struct inode *inode) +{ + unsigned add_flags = DCACHE_FILE_TYPE; + + if (!inode) + return DCACHE_MISS_TYPE; + + if (S_ISDIR(inode->i_mode)) { + add_flags = DCACHE_DIRECTORY_TYPE; + if (unlikely(!(inode->i_opflags & IOP_LOOKUP))) { + if (unlikely(!inode->i_op->lookup)) + add_flags = DCACHE_AUTODIR_TYPE; + else + inode->i_opflags |= IOP_LOOKUP; + } + } else if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { + if (unlikely(inode->i_op->follow_link)) + add_flags = DCACHE_SYMLINK_TYPE; + else + inode->i_opflags |= IOP_NOFOLLOW; + } + + if (unlikely(IS_AUTOMOUNT(inode))) + add_flags |= DCACHE_NEED_AUTOMOUNT; + return add_flags; +} + static void __d_instantiate(struct dentry *dentry, struct inode *inode) { + unsigned add_flags = d_flags_for_inode(inode); + spin_lock(&dentry->d_lock); - if (inode) { - if (unlikely(IS_AUTOMOUNT(inode))) - dentry->d_flags |= DCACHE_NEED_AUTOMOUNT; + dentry->d_flags &= ~DCACHE_ENTRY_TYPE; + dentry->d_flags |= add_flags; + if (inode) hlist_add_head(&dentry->d_alias, &inode->i_dentry); - } dentry->d_inode = inode; dentry_rcuwalk_barrier(dentry); spin_unlock(&dentry->d_lock); @@ -1801,6 +1803,33 @@ struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode) EXPORT_SYMBOL(d_instantiate_unique); +/** + * d_instantiate_no_diralias - instantiate a non-aliased dentry + * @entry: dentry to complete + * @inode: inode to attach to this dentry + * + * Fill in inode information in the entry. If a directory alias is found, then + * return an error (and drop inode). Together with d_materialise_unique() this + * guarantees that a directory inode may never have more than one alias. + */ +int d_instantiate_no_diralias(struct dentry *entry, struct inode *inode) +{ + BUG_ON(!hlist_unhashed(&entry->d_alias)); + + spin_lock(&inode->i_lock); + if (S_ISDIR(inode->i_mode) && !hlist_empty(&inode->i_dentry)) { + spin_unlock(&inode->i_lock); + iput(inode); + return -EBUSY; + } + __d_instantiate(entry, inode); + spin_unlock(&inode->i_lock); + security_d_instantiate(entry, inode); + + return 0; +} +EXPORT_SYMBOL(d_instantiate_no_diralias); + struct dentry *d_make_root(struct inode *root_inode) { struct dentry *res = NULL; @@ -1870,6 +1899,7 @@ struct dentry *d_obtain_alias(struct inode *inode) static const struct qstr anonstring = QSTR_INIT("/", 1); struct dentry *tmp; struct dentry *res; + unsigned add_flags; if (!inode) return ERR_PTR(-ESTALE); @@ -1895,9 +1925,11 @@ struct dentry *d_obtain_alias(struct inode *inode) } /* attach a disconnected dentry */ + add_flags = d_flags_for_inode(inode) | DCACHE_DISCONNECTED; + spin_lock(&tmp->d_lock); tmp->d_inode = inode; - tmp->d_flags |= DCACHE_DISCONNECTED; + tmp->d_flags |= add_flags; hlist_add_head(&tmp->d_alias, &inode->i_dentry); hlist_bl_lock(&tmp->d_sb->s_anon); hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon); @@ -2725,7 +2757,6 @@ static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) spin_unlock(&dentry->d_lock); /* anon->d_lock still locked, returns locked */ - anon->d_flags &= ~DCACHE_DISCONNECTED; } /** @@ -2881,27 +2912,36 @@ static int prepend_path(const struct path *path, const struct path *root, char **buffer, int *buflen) { - struct dentry *dentry = path->dentry; - struct vfsmount *vfsmnt = path->mnt; - struct mount *mnt = real_mount(vfsmnt); + struct dentry *dentry; + struct vfsmount *vfsmnt; + struct mount *mnt; int error = 0; - unsigned seq = 0; + unsigned seq, m_seq = 0; char *bptr; int blen; rcu_read_lock(); +restart_mnt: + read_seqbegin_or_lock(&mount_lock, &m_seq); + seq = 0; + rcu_read_lock(); restart: bptr = *buffer; blen = *buflen; + error = 0; + dentry = path->dentry; + vfsmnt = path->mnt; + mnt = real_mount(vfsmnt); read_seqbegin_or_lock(&rename_lock, &seq); while (dentry != root->dentry || vfsmnt != root->mnt) { struct dentry * parent; if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { + struct mount *parent = ACCESS_ONCE(mnt->mnt_parent); /* Global root? */ - if (mnt_has_parent(mnt)) { - dentry = mnt->mnt_mountpoint; - mnt = mnt->mnt_parent; + if (mnt != parent) { + dentry = ACCESS_ONCE(mnt->mnt_mountpoint); + mnt = parent; vfsmnt = &mnt->mnt; continue; } @@ -2936,6 +2976,14 @@ restart: } done_seqretry(&rename_lock, seq); + if (!(m_seq & 1)) + rcu_read_unlock(); + if (need_seqretry(&mount_lock, m_seq)) { + m_seq = 1; + goto restart_mnt; + } + done_seqretry(&mount_lock, m_seq); + if (error >= 0 && bptr == *buffer) { if (--blen < 0) error = -ENAMETOOLONG; @@ -2971,9 +3019,7 @@ char *__d_path(const struct path *path, int error; prepend(&res, &buflen, "\0", 1); - br_read_lock(&vfsmount_lock); error = prepend_path(path, root, &res, &buflen); - br_read_unlock(&vfsmount_lock); if (error < 0) return ERR_PTR(error); @@ -2990,9 +3036,7 @@ char *d_absolute_path(const struct path *path, int error; prepend(&res, &buflen, "\0", 1); - br_read_lock(&vfsmount_lock); error = prepend_path(path, &root, &res, &buflen); - br_read_unlock(&vfsmount_lock); if (error > 1) error = -EINVAL; @@ -3067,9 +3111,7 @@ char *d_path(const struct path *path, char *buf, int buflen) rcu_read_lock(); get_fs_root_rcu(current->fs, &root); - br_read_lock(&vfsmount_lock); error = path_with_deleted(path, &root, &res, &buflen); - br_read_unlock(&vfsmount_lock); rcu_read_unlock(); if (error < 0) @@ -3224,7 +3266,6 @@ SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) get_fs_root_and_pwd_rcu(current->fs, &root, &pwd); error = -ENOENT; - br_read_lock(&vfsmount_lock); if (!d_unlinked(pwd.dentry)) { unsigned long len; char *cwd = page + PATH_MAX; @@ -3232,7 +3273,6 @@ SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) prepend(&cwd, &buflen, "\0", 1); error = prepend_path(&pwd, &root, &cwd, &buflen); - br_read_unlock(&vfsmount_lock); rcu_read_unlock(); if (error < 0) @@ -3253,7 +3293,6 @@ SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) error = -EFAULT; } } else { - br_read_unlock(&vfsmount_lock); rcu_read_unlock(); } |