From 01ddc4ede5f09cdaed015d49ab66eec179085a2e Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 5 Sep 2013 11:44:34 +0200 Subject: vfs: restructure d_genocide() It shouldn't matter when we decrement the refcount during the walk as long as we do it exactly once. Restructure d_genocide() to do the killing on entering the dentry instead of when leaving it. This helps creating a common helper for tree walking. Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- fs/dcache.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) (limited to 'fs') diff --git a/fs/dcache.c b/fs/dcache.c index 5aa53bc056ba..f792e9f20eca 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -2952,6 +2952,10 @@ resume: spin_unlock(&dentry->d_lock); continue; } + if (!(dentry->d_flags & DCACHE_GENOCIDE)) { + dentry->d_flags |= DCACHE_GENOCIDE; + dentry->d_lockref.count--; + } if (!list_empty(&dentry->d_subdirs)) { spin_unlock(&this_parent->d_lock); spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); @@ -2959,18 +2963,10 @@ resume: spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); goto repeat; } - if (!(dentry->d_flags & DCACHE_GENOCIDE)) { - dentry->d_flags |= DCACHE_GENOCIDE; - dentry->d_lockref.count--; - } spin_unlock(&dentry->d_lock); } if (this_parent != root) { struct dentry *child = this_parent; - if (!(this_parent->d_flags & DCACHE_GENOCIDE)) { - this_parent->d_flags |= DCACHE_GENOCIDE; - this_parent->d_lockref.count--; - } this_parent = try_to_ascend(this_parent, locked, seq); if (!this_parent) goto rename_retry; -- cgit v1.2.3-59-g8ed1b From db14fc3abcd5dcc9b32ad5b9dd5b8f9e16295a39 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 5 Sep 2013 11:44:35 +0200 Subject: vfs: add d_walk() This one replaces three instances open coded tree walking (have_submounts, select_parent, d_genocide) with a common helper. In addition to slightly reducing the kernel size, this simplifies the callers and makes them less bug prone. Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- fs/dcache.c | 309 +++++++++++++++++++++++++++++------------------------------- 1 file changed, 148 insertions(+), 161 deletions(-) (limited to 'fs') diff --git a/fs/dcache.c b/fs/dcache.c index f792e9f20eca..043c5b478a77 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1031,34 +1031,56 @@ static struct dentry *try_to_ascend(struct dentry *old, int locked, unsigned seq return new; } +/** + * enum d_walk_ret - action to talke during tree walk + * @D_WALK_CONTINUE: contrinue walk + * @D_WALK_QUIT: quit walk + * @D_WALK_NORETRY: quit when retry is needed + * @D_WALK_SKIP: skip this dentry and its children + */ +enum d_walk_ret { + D_WALK_CONTINUE, + D_WALK_QUIT, + D_WALK_NORETRY, + D_WALK_SKIP, +}; -/* - * Search for at least 1 mount point in the dentry's subdirs. - * We descend to the next level whenever the d_subdirs - * list is non-empty and continue searching. - */ - /** - * have_submounts - check for mounts over a dentry - * @parent: dentry to check. + * d_walk - walk the dentry tree + * @parent: start of walk + * @data: data passed to @enter() and @finish() + * @enter: callback when first entering the dentry + * @finish: callback when successfully finished the walk * - * Return true if the parent or its subdirectories contain - * a mount point + * The @enter() and @finish() callbacks are called with d_lock held. */ -int have_submounts(struct dentry *parent) +static void d_walk(struct dentry *parent, void *data, + enum d_walk_ret (*enter)(void *, struct dentry *), + void (*finish)(void *)) { struct dentry *this_parent; struct list_head *next; unsigned seq; int locked = 0; + enum d_walk_ret ret; + bool retry = true; seq = read_seqbegin(&rename_lock); again: this_parent = parent; - - if (d_mountpoint(parent)) - goto positive; spin_lock(&this_parent->d_lock); + + ret = enter(data, this_parent); + switch (ret) { + case D_WALK_CONTINUE: + break; + case D_WALK_QUIT: + case D_WALK_SKIP: + goto out_unlock; + case D_WALK_NORETRY: + retry = false; + break; + } repeat: next = this_parent->d_subdirs.next; resume: @@ -1068,12 +1090,22 @@ resume: next = tmp->next; spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); - /* Have we found a mount point ? */ - if (d_mountpoint(dentry)) { + + ret = enter(data, dentry); + switch (ret) { + case D_WALK_CONTINUE: + break; + case D_WALK_QUIT: spin_unlock(&dentry->d_lock); - spin_unlock(&this_parent->d_lock); - goto positive; + goto out_unlock; + case D_WALK_NORETRY: + retry = false; + break; + case D_WALK_SKIP: + spin_unlock(&dentry->d_lock); + continue; } + if (!list_empty(&dentry->d_subdirs)) { spin_unlock(&this_parent->d_lock); spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); @@ -1094,26 +1126,61 @@ resume: next = child->d_u.d_child.next; goto resume; } - spin_unlock(&this_parent->d_lock); - if (!locked && read_seqretry(&rename_lock, seq)) - goto rename_retry; - if (locked) - write_sequnlock(&rename_lock); - return 0; /* No mount points found in tree */ -positive: - if (!locked && read_seqretry(&rename_lock, seq)) + if (!locked && read_seqretry(&rename_lock, seq)) { + spin_unlock(&this_parent->d_lock); goto rename_retry; + } + if (finish) + finish(data); + +out_unlock: + spin_unlock(&this_parent->d_lock); if (locked) write_sequnlock(&rename_lock); - return 1; + return; rename_retry: + if (!retry) + return; if (locked) goto again; locked = 1; write_seqlock(&rename_lock); goto again; } + +/* + * Search for at least 1 mount point in the dentry's subdirs. + * We descend to the next level whenever the d_subdirs + * 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; + if (d_mountpoint(dentry)) { + *ret = 1; + return D_WALK_QUIT; + } + return D_WALK_CONTINUE; +} + +int have_submounts(struct dentry *parent) +{ + int ret = 0; + + d_walk(parent, &ret, check_mount, NULL); + + return ret; +} EXPORT_SYMBOL(have_submounts); /* @@ -1130,93 +1197,46 @@ EXPORT_SYMBOL(have_submounts); * drop the lock and return early due to latency * constraints. */ -static int select_parent(struct dentry *parent, struct list_head *dispose) -{ - struct dentry *this_parent; - struct list_head *next; - unsigned seq; - int found = 0; - int locked = 0; - seq = read_seqbegin(&rename_lock); -again: - this_parent = parent; - spin_lock(&this_parent->d_lock); -repeat: - next = this_parent->d_subdirs.next; -resume: - while (next != &this_parent->d_subdirs) { - struct list_head *tmp = next; - struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); - next = tmp->next; - - spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); +struct select_data { + struct dentry *start; + struct list_head dispose; + int found; +}; - /* - * move only zero ref count dentries to the dispose list. - * - * Those which are presently on the shrink list, being processed - * by shrink_dentry_list(), shouldn't be moved. Otherwise the - * loop in shrink_dcache_parent() might not make any progress - * and loop forever. - */ - if (dentry->d_lockref.count) { - dentry_lru_del(dentry); - } else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) { - dentry_lru_move_list(dentry, dispose); - dentry->d_flags |= DCACHE_SHRINK_LIST; - found++; - } - /* - * We can return to the caller if we have found some (this - * ensures forward progress). We'll be coming back to find - * the rest. - */ - if (found && need_resched()) { - spin_unlock(&dentry->d_lock); - goto out; - } +static enum d_walk_ret select_collect(void *_data, struct dentry *dentry) +{ + struct select_data *data = _data; + enum d_walk_ret ret = D_WALK_CONTINUE; - /* - * Descend a level if the d_subdirs list is non-empty. - */ - if (!list_empty(&dentry->d_subdirs)) { - spin_unlock(&this_parent->d_lock); - spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); - this_parent = dentry; - spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); - goto repeat; - } + if (data->start == dentry) + goto out; - spin_unlock(&dentry->d_lock); - } /* - * All done at this level ... ascend and resume the search. + * move only zero ref count dentries to the dispose list. + * + * Those which are presently on the shrink list, being processed + * by shrink_dentry_list(), shouldn't be moved. Otherwise the + * loop in shrink_dcache_parent() might not make any progress + * and loop forever. */ - if (this_parent != parent) { - struct dentry *child = this_parent; - this_parent = try_to_ascend(this_parent, locked, seq); - if (!this_parent) - goto rename_retry; - next = child->d_u.d_child.next; - goto resume; + if (dentry->d_lockref.count) { + dentry_lru_del(dentry); + } else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) { + dentry_lru_move_list(dentry, &data->dispose); + dentry->d_flags |= DCACHE_SHRINK_LIST; + data->found++; + ret = D_WALK_NORETRY; } + /* + * We can return to the caller if we have found some (this + * ensures forward progress). We'll be coming back to find + * the rest. + */ + if (data->found && need_resched()) + ret = D_WALK_QUIT; out: - spin_unlock(&this_parent->d_lock); - if (!locked && read_seqretry(&rename_lock, seq)) - goto rename_retry; - if (locked) - write_sequnlock(&rename_lock); - return found; - -rename_retry: - if (found) - return found; - if (locked) - goto again; - locked = 1; - write_seqlock(&rename_lock); - goto again; + return ret; } /** @@ -1225,13 +1245,20 @@ rename_retry: * * Prune the dcache to remove unused children of the parent dentry. */ -void shrink_dcache_parent(struct dentry * parent) +void shrink_dcache_parent(struct dentry *parent) { - LIST_HEAD(dispose); - int found; + for (;;) { + struct select_data data; - while ((found = select_parent(parent, &dispose)) != 0) { - shrink_dentry_list(&dispose); + INIT_LIST_HEAD(&data.dispose); + data.start = parent; + data.found = 0; + + d_walk(parent, &data, select_collect, NULL); + if (!data.found) + break; + + shrink_dentry_list(&data.dispose); cond_resched(); } } @@ -2928,64 +2955,24 @@ int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry) return result; } -void d_genocide(struct dentry *root) +static enum d_walk_ret d_genocide_kill(void *data, struct dentry *dentry) { - struct dentry *this_parent; - struct list_head *next; - unsigned seq; - int locked = 0; + struct dentry *root = data; + if (dentry != root) { + if (d_unhashed(dentry) || !dentry->d_inode) + return D_WALK_SKIP; - seq = read_seqbegin(&rename_lock); -again: - this_parent = root; - spin_lock(&this_parent->d_lock); -repeat: - next = this_parent->d_subdirs.next; -resume: - while (next != &this_parent->d_subdirs) { - struct list_head *tmp = next; - struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); - next = tmp->next; - - spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); - if (d_unhashed(dentry) || !dentry->d_inode) { - spin_unlock(&dentry->d_lock); - continue; - } if (!(dentry->d_flags & DCACHE_GENOCIDE)) { dentry->d_flags |= DCACHE_GENOCIDE; dentry->d_lockref.count--; } - if (!list_empty(&dentry->d_subdirs)) { - spin_unlock(&this_parent->d_lock); - spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); - this_parent = dentry; - spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); - goto repeat; - } - spin_unlock(&dentry->d_lock); } - if (this_parent != root) { - struct dentry *child = this_parent; - this_parent = try_to_ascend(this_parent, locked, seq); - if (!this_parent) - goto rename_retry; - next = child->d_u.d_child.next; - goto resume; - } - spin_unlock(&this_parent->d_lock); - if (!locked && read_seqretry(&rename_lock, seq)) - goto rename_retry; - if (locked) - write_sequnlock(&rename_lock); - return; + return D_WALK_CONTINUE; +} -rename_retry: - if (locked) - goto again; - locked = 1; - write_seqlock(&rename_lock); - goto again; +void d_genocide(struct dentry *parent) +{ + d_walk(parent, parent, d_genocide_kill, NULL); } void d_tmpfile(struct dentry *dentry, struct inode *inode) -- cgit v1.2.3-59-g8ed1b From 848ac114e847af3f1f9141c90a39ebe79bdb13b3 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 5 Sep 2013 11:44:36 +0200 Subject: vfs: check submounts and drop atomically We check submounts before doing d_drop() on a non-empty directory dentry in NFS (have_submounts()), but we do not exclude a racing mount. Process A: have_submounts() -> returns false Process B: mount() -> success Process A: d_drop() This patch prepares the ground for the fix by doing the following operations all under the same rename lock: have_submounts() shrink_dcache_parent() d_drop() This is actually an optimization since have_submounts() and shrink_dcache_parent() both traverse the same dentry tree separately. Signed-off-by: Miklos Szeredi CC: David Howells CC: Steven Whitehouse CC: Trond Myklebust CC: Greg Kroah-Hartman Signed-off-by: Al Viro --- fs/dcache.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/dcache.h | 1 + 2 files changed, 66 insertions(+) (limited to 'fs') diff --git a/fs/dcache.c b/fs/dcache.c index 043c5b478a77..ce5a7e6d84cd 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1264,6 +1264,71 @@ void shrink_dcache_parent(struct dentry *parent) } EXPORT_SYMBOL(shrink_dcache_parent); +static enum d_walk_ret check_and_collect(void *_data, struct dentry *dentry) +{ + struct select_data *data = _data; + + if (d_mountpoint(dentry)) { + data->found = -EBUSY; + return D_WALK_QUIT; + } + + return select_collect(_data, dentry); +} + +static void check_and_drop(void *_data) +{ + struct select_data *data = _data; + + if (d_mountpoint(data->start)) + data->found = -EBUSY; + if (!data->found) + __d_drop(data->start); +} + +/** + * check_submounts_and_drop - prune dcache, check for submounts and drop + * + * All done as a single atomic operation relative to has_unlinked_ancestor(). + * Returns 0 if successfully unhashed @parent. If there were submounts then + * return -EBUSY. + * + * @dentry: dentry to prune and drop + */ +int check_submounts_and_drop(struct dentry *dentry) +{ + int ret = 0; + + /* Negative dentries can be dropped without further checks */ + if (!dentry->d_inode) { + d_drop(dentry); + goto out; + } + + for (;;) { + struct select_data data; + + INIT_LIST_HEAD(&data.dispose); + data.start = dentry; + data.found = 0; + + d_walk(dentry, &data, check_and_collect, check_and_drop); + ret = data.found; + + if (!list_empty(&data.dispose)) + shrink_dentry_list(&data.dispose); + + if (ret <= 0) + break; + + cond_resched(); + } + +out: + return ret; +} +EXPORT_SYMBOL(check_submounts_and_drop); + /** * __d_alloc - allocate a dcache entry * @sb: filesystem it will belong to diff --git a/include/linux/dcache.h b/include/linux/dcache.h index 9169b91ea2d2..c6d3fe50ff96 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -253,6 +253,7 @@ extern void d_prune_aliases(struct inode *); /* test whether we have any submounts in a subdir tree */ extern int have_submounts(struct dentry *); +extern int check_submounts_and_drop(struct dentry *); /* * This adds the entry to the hash queues. -- cgit v1.2.3-59-g8ed1b From eed810076685c77dc9a8c5c3593e641c93caed1c Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 5 Sep 2013 14:39:11 +0200 Subject: vfs: check unlinked ancestors before mount We check submounts before doing d_drop() on a non-empty directory dentry in NFS (have_submounts()), but we do not exclude a racing mount. Nor do we prevent mounts to be added to the disconnected subtree using relative paths after the d_drop(). This patch fixes these issues by checking for unlinked (unhashed, non-root) ancestors before proceeding with the mount. This is done with rename seqlock taken for write and with ->d_lock grabbed on each ancestor in turn, including our dentry itself. This ensures that the only one of check_submounts_and_drop() or has_unlinked_ancestor() can succeed. Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- fs/dcache.c | 33 +++++++++++++++++++++++++++++++++ fs/internal.h | 1 + fs/namespace.c | 11 +++++------ 3 files changed, 39 insertions(+), 6 deletions(-) (limited to 'fs') diff --git a/fs/dcache.c b/fs/dcache.c index ce5a7e6d84cd..761e31bacbc2 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1183,6 +1183,39 @@ int have_submounts(struct dentry *parent) } EXPORT_SYMBOL(have_submounts); +/* + * Called by mount code to set a mountpoint and check if the mountpoint is + * reachable (e.g. NFS can unhash a directory dentry and then the complete + * subtree can become unreachable). + * + * Only one of check_submounts_and_drop() and d_set_mounted() must succeed. For + * this reason take rename_lock and d_lock on dentry and ancestors. + */ +int d_set_mounted(struct dentry *dentry) +{ + struct dentry *p; + int ret = -ENOENT; + write_seqlock(&rename_lock); + for (p = dentry->d_parent; !IS_ROOT(p); p = p->d_parent) { + /* Need exclusion wrt. check_submounts_and_drop() */ + spin_lock(&p->d_lock); + if (unlikely(d_unhashed(p))) { + spin_unlock(&p->d_lock); + goto out; + } + spin_unlock(&p->d_lock); + } + spin_lock(&dentry->d_lock); + if (!d_unlinked(dentry)) { + dentry->d_flags |= DCACHE_MOUNTED; + ret = 0; + } + spin_unlock(&dentry->d_lock); +out: + write_sequnlock(&rename_lock); + return ret; +} + /* * Search the dentry child list of the specified parent, * and move any unused dentries to the end of the unused diff --git a/fs/internal.h b/fs/internal.h index 7c5f01cf619d..d20893795526 100644 --- a/fs/internal.h +++ b/fs/internal.h @@ -126,6 +126,7 @@ extern int invalidate_inodes(struct super_block *, bool); * dcache.c */ extern struct dentry *__d_alloc(struct super_block *, const struct qstr *); +extern int d_set_mounted(struct dentry *dentry); /* * read_write.c diff --git a/fs/namespace.c b/fs/namespace.c index ad8ea9bc2518..5997887cc64a 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -611,6 +611,7 @@ static struct mountpoint *new_mountpoint(struct dentry *dentry) { struct list_head *chain = mountpoint_hashtable + hash(NULL, dentry); struct mountpoint *mp; + int ret; list_for_each_entry(mp, chain, m_hash) { if (mp->m_dentry == dentry) { @@ -626,14 +627,12 @@ static struct mountpoint *new_mountpoint(struct dentry *dentry) if (!mp) return ERR_PTR(-ENOMEM); - spin_lock(&dentry->d_lock); - if (d_unlinked(dentry)) { - spin_unlock(&dentry->d_lock); + ret = d_set_mounted(dentry); + if (ret) { kfree(mp); - return ERR_PTR(-ENOENT); + return ERR_PTR(ret); } - dentry->d_flags |= DCACHE_MOUNTED; - spin_unlock(&dentry->d_lock); + mp->m_dentry = dentry; mp->m_count = 1; list_add(&mp->m_hash, chain); -- cgit v1.2.3-59-g8ed1b From ba81238076d368b9bb78a7fbf6c621b49d4d602f Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 5 Sep 2013 11:44:38 +0200 Subject: afs: use check_submounts_and_drop() Do have_submounts(), shrink_dcache_parent() and d_drop() atomically. check_submounts_and_drop() can deal with negative dentries as well. Signed-off-by: Miklos Szeredi CC: David Howells Signed-off-by: Al Viro --- fs/afs/dir.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) (limited to 'fs') diff --git a/fs/afs/dir.c b/fs/afs/dir.c index 34494fbead0a..0b74d3176ab7 100644 --- a/fs/afs/dir.c +++ b/fs/afs/dir.c @@ -685,16 +685,12 @@ not_found: spin_unlock(&dentry->d_lock); out_bad: - if (dentry->d_inode) { - /* don't unhash if we have submounts */ - if (have_submounts(dentry)) - goto out_skip; - } + /* don't unhash if we have submounts */ + if (check_submounts_and_drop(dentry) != 0) + goto out_skip; _debug("dropping dentry %s/%s", parent->d_name.name, dentry->d_name.name); - shrink_dcache_parent(dentry); - d_drop(dentry); dput(parent); key_put(key); -- cgit v1.2.3-59-g8ed1b From 1191a2bdf012147c33e5fa95255974a3f7bf6e2f Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 5 Sep 2013 11:44:39 +0200 Subject: gfs2: use check_submounts_and_drop() Do have_submounts(), shrink_dcache_parent() and d_drop() atomically. check_submounts_and_drop() can deal with negative dentries and non-directories as well. Non-directories can also be mounted on. And just like directories we don't want these to disappear with invalidation. Signed-off-by: Miklos Szeredi CC: Steven Whitehouse Signed-off-by: Al Viro --- fs/gfs2/dentry.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) (limited to 'fs') diff --git a/fs/gfs2/dentry.c b/fs/gfs2/dentry.c index f2448ab2aac5..d3a5d4e29ba5 100644 --- a/fs/gfs2/dentry.c +++ b/fs/gfs2/dentry.c @@ -93,12 +93,9 @@ invalid_gunlock: if (!had_lock) gfs2_glock_dq_uninit(&d_gh); invalid: - if (inode && S_ISDIR(inode->i_mode)) { - if (have_submounts(dentry)) - goto valid; - shrink_dcache_parent(dentry); - } - d_drop(dentry); + if (check_submounts_and_drop(dentry) != 0) + goto valid; + dput(parent); return 0; -- cgit v1.2.3-59-g8ed1b From 13caa9fb5b4ce040379523037a0ce4ef867ee0c0 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 5 Sep 2013 11:44:40 +0200 Subject: nfs: use check_submounts_and_drop() Do have_submounts(), shrink_dcache_parent() and d_drop() atomically. check_submounts_and_drop() can deal with negative dentries and non-directories as well. Non-directories can also be mounted on. And just like directories we don't want these to disappear with invalidation. Signed-off-by: Miklos Szeredi CC: Trond Myklebust Signed-off-by: Al Viro --- fs/nfs/dir.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) (limited to 'fs') diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index e474ca2b2bfe..7468735d299e 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -1135,14 +1135,13 @@ out_zap_parent: if (inode && S_ISDIR(inode->i_mode)) { /* Purge readdir caches. */ nfs_zap_caches(inode); - /* If we have submounts, don't unhash ! */ - if (have_submounts(dentry)) - goto out_valid; if (dentry->d_flags & DCACHE_DISCONNECTED) goto out_valid; - shrink_dcache_parent(dentry); } - d_drop(dentry); + /* If we have submounts, don't unhash ! */ + if (check_submounts_and_drop(dentry) != 0) + goto out_valid; + dput(parent); dfprintk(LOOKUPCACHE, "NFS: %s(%s/%s) is invalid\n", __func__, dentry->d_parent->d_name.name, -- cgit v1.2.3-59-g8ed1b From 6497d160f6abf8d1082ff1a4efd841118cb1fddd Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 5 Sep 2013 11:44:41 +0200 Subject: sysfs: use check_submounts_and_drop() Do have_submounts(), shrink_dcache_parent() and d_drop() atomically. check_submounts_and_drop() can deal with negative dentries and non-directories as well. Non-directories can also be mounted on. And just like directories we don't want these to disappear with invalidation. Signed-off-by: Miklos Szeredi Acked-by: Greg Kroah-Hartman Signed-off-by: Al Viro --- fs/sysfs/dir.c | 20 ++++++++------------ 1 file changed, 8 insertions(+), 12 deletions(-) (limited to 'fs') diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c index 99ec5b40e977..4d83cedb9fcb 100644 --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -297,7 +297,6 @@ static int sysfs_dentry_delete(const struct dentry *dentry) static int sysfs_dentry_revalidate(struct dentry *dentry, unsigned int flags) { struct sysfs_dirent *sd; - int is_dir; int type; if (flags & LOOKUP_RCU) @@ -341,18 +340,15 @@ out_bad: * is performed at its new name the dentry will be readded * to the dcache hashes. */ - is_dir = (sysfs_type(sd) == SYSFS_DIR); mutex_unlock(&sysfs_mutex); - if (is_dir) { - /* If we have submounts we must allow the vfs caches - * to lie about the state of the filesystem to prevent - * leaks and other nasty things. - */ - if (have_submounts(dentry)) - goto out_valid; - shrink_dcache_parent(dentry); - } - d_drop(dentry); + + /* If we have submounts we must allow the vfs caches + * to lie about the state of the filesystem to prevent + * leaks and other nasty things. + */ + if (check_submounts_and_drop(dentry) != 0) + goto out_valid; + return 0; } -- cgit v1.2.3-59-g8ed1b From 5835f3390e35ae3da9add646a2ca2cc30b47370e Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 5 Sep 2013 11:44:42 +0200 Subject: fuse: use d_materialise_unique() Use d_materialise_unique() instead of d_splice_alias(). This allows dentry subtrees to be moved to a new place if there moved, even if something is referencing a dentry in the subtree (open fd, cwd, etc..). This will also allow us to drop a subtree if it is found to be replaced by something else. In this case the disconnected subtree can later be reconnected to its new location. d_materialise_unique() ensures that a directory entry only ever has one alias. We keep fc->inst_mutex around the calls for d_materialise_unique() on directories to prevent a race with mkdir "stealing" the inode. Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- fs/fuse/dir.c | 69 ++++++++++++++++++++++------------------------------------- 1 file changed, 26 insertions(+), 43 deletions(-) (limited to 'fs') diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index 72a5d5b04494..131d14b604ef 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -267,26 +267,6 @@ int fuse_valid_type(int m) S_ISBLK(m) || S_ISFIFO(m) || S_ISSOCK(m); } -/* - * Add a directory inode to a dentry, ensuring that no other dentry - * refers to this inode. Called with fc->inst_mutex. - */ -static struct dentry *fuse_d_add_directory(struct dentry *entry, - struct inode *inode) -{ - struct dentry *alias = d_find_alias(inode); - if (alias && !(alias->d_flags & DCACHE_DISCONNECTED)) { - /* This tries to shrink the subtree below alias */ - fuse_invalidate_entry(alias); - dput(alias); - if (!hlist_empty(&inode->i_dentry)) - return ERR_PTR(-EBUSY); - } else { - dput(alias); - } - return d_splice_alias(inode, entry); -} - int fuse_lookup_name(struct super_block *sb, u64 nodeid, struct qstr *name, struct fuse_entry_out *outarg, struct inode **inode) { @@ -345,6 +325,24 @@ int fuse_lookup_name(struct super_block *sb, u64 nodeid, struct qstr *name, return err; } +static struct dentry *fuse_materialise_dentry(struct dentry *dentry, + struct inode *inode) +{ + struct dentry *newent; + + if (inode && S_ISDIR(inode->i_mode)) { + struct fuse_conn *fc = get_fuse_conn(inode); + + mutex_lock(&fc->inst_mutex); + newent = d_materialise_unique(dentry, inode); + mutex_unlock(&fc->inst_mutex); + } else { + newent = d_materialise_unique(dentry, inode); + } + + return newent; +} + static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry, unsigned int flags) { @@ -352,7 +350,6 @@ static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry, struct fuse_entry_out outarg; struct inode *inode; struct dentry *newent; - struct fuse_conn *fc = get_fuse_conn(dir); bool outarg_valid = true; err = fuse_lookup_name(dir->i_sb, get_node_id(dir), &entry->d_name, @@ -368,16 +365,10 @@ static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry, if (inode && get_node_id(inode) == FUSE_ROOT_ID) goto out_iput; - if (inode && S_ISDIR(inode->i_mode)) { - mutex_lock(&fc->inst_mutex); - newent = fuse_d_add_directory(entry, inode); - mutex_unlock(&fc->inst_mutex); - err = PTR_ERR(newent); - if (IS_ERR(newent)) - goto out_iput; - } else { - newent = d_splice_alias(inode, entry); - } + newent = fuse_materialise_dentry(entry, inode); + err = PTR_ERR(newent); + if (IS_ERR(newent)) + goto out_err; entry = newent ? newent : entry; if (outarg_valid) @@ -1275,18 +1266,10 @@ static int fuse_direntplus_link(struct file *file, if (!inode) goto out; - if (S_ISDIR(inode->i_mode)) { - mutex_lock(&fc->inst_mutex); - alias = fuse_d_add_directory(dentry, inode); - mutex_unlock(&fc->inst_mutex); - err = PTR_ERR(alias); - if (IS_ERR(alias)) { - iput(inode); - goto out; - } - } else { - alias = d_splice_alias(inode, dentry); - } + alias = fuse_materialise_dentry(dentry, inode); + err = PTR_ERR(alias); + if (IS_ERR(alias)) + goto out; if (alias) { dput(dentry); -- cgit v1.2.3-59-g8ed1b From e2a6b95236eba5341253a2e4a50946355f887303 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 5 Sep 2013 11:44:43 +0200 Subject: fuse: clean up return in fuse_dentry_revalidate() On errors unrelated to the filesystem's state (ENOMEM, ENOTCONN) return the error itself from ->d_revalidate() insted of returning zero (invalid). Also make a common label for invalidating the dentry. This will be used by the next patch. Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- fs/fuse/dir.c | 26 ++++++++++++++++++-------- 1 file changed, 18 insertions(+), 8 deletions(-) (limited to 'fs') diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index 131d14b604ef..25c6cfe98801 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -182,10 +182,11 @@ static int fuse_dentry_revalidate(struct dentry *entry, unsigned int flags) struct inode *inode; struct dentry *parent; struct fuse_conn *fc; + int ret; inode = ACCESS_ONCE(entry->d_inode); if (inode && is_bad_inode(inode)) - return 0; + goto invalid; else if (fuse_dentry_time(entry) < get_jiffies_64()) { int err; struct fuse_entry_out outarg; @@ -195,20 +196,23 @@ static int fuse_dentry_revalidate(struct dentry *entry, unsigned int flags) /* For negative dentries, always do a fresh lookup */ if (!inode) - return 0; + goto invalid; + ret = -ECHILD; if (flags & LOOKUP_RCU) - return -ECHILD; + goto out; fc = get_fuse_conn(inode); req = fuse_get_req_nopages(fc); + ret = PTR_ERR(req); if (IS_ERR(req)) - return 0; + goto out; forget = fuse_alloc_forget(); if (!forget) { fuse_put_request(fc, req); - return 0; + ret = -ENOMEM; + goto out; } attr_version = fuse_get_attr_version(fc); @@ -227,7 +231,7 @@ static int fuse_dentry_revalidate(struct dentry *entry, unsigned int flags) struct fuse_inode *fi = get_fuse_inode(inode); if (outarg.nodeid != get_node_id(inode)) { fuse_queue_forget(fc, forget, outarg.nodeid, 1); - return 0; + goto invalid; } spin_lock(&fc->lock); fi->nlookup++; @@ -235,7 +239,7 @@ static int fuse_dentry_revalidate(struct dentry *entry, unsigned int flags) } kfree(forget); if (err || (outarg.attr.mode ^ inode->i_mode) & S_IFMT) - return 0; + goto invalid; fuse_change_attributes(inode, &outarg.attr, entry_attr_timeout(&outarg), @@ -249,7 +253,13 @@ static int fuse_dentry_revalidate(struct dentry *entry, unsigned int flags) dput(parent); } } - return 1; + ret = 1; +out: + return ret; + +invalid: + ret = 0; + goto out; } static int invalid_nodeid(u64 nodeid) -- cgit v1.2.3-59-g8ed1b From 46ea1562da792a94ee8391f7aed882eb7771e18c Mon Sep 17 00:00:00 2001 From: Anand Avati Date: Thu, 5 Sep 2013 11:44:44 +0200 Subject: fuse: drop dentry on failed revalidate Drop a subtree when we find that it has moved or been delated. This can be done as long as there are no submounts under this location. If the directory was moved and we come across the same directory in a future lookup it will be reconnected by d_materialise_unique(). Signed-off-by: Anand Avati Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- fs/fuse/dir.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'fs') diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index 25c6cfe98801..0e6961aae6c0 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -259,6 +259,8 @@ out: invalid: ret = 0; + if (check_submounts_and_drop(entry) != 0) + ret = 1; goto out; } -- cgit v1.2.3-59-g8ed1b