From 6f18493e541c690169c3b1479d47d95f624161cf Mon Sep 17 00:00:00 2001 From: Al Viro Date: Thu, 11 Sep 2014 18:55:50 -0400 Subject: move the call of __d_drop(anon) into __d_materialise_unique(dentry, anon) and lock the right list there Cc: stable@vger.kernel.org Signed-off-by: Al Viro --- fs/dcache.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'fs') diff --git a/fs/dcache.c b/fs/dcache.c index d30ce699ae4b..5c6e71dc23f5 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -2656,6 +2656,12 @@ static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) dentry->d_parent = dentry; list_del_init(&dentry->d_u.d_child); anon->d_parent = dparent; + if (likely(!d_unhashed(anon))) { + hlist_bl_lock(&anon->d_sb->s_anon); + __hlist_bl_del(&anon->d_hash); + anon->d_hash.pprev = NULL; + hlist_bl_unlock(&anon->d_sb->s_anon); + } list_move(&anon->d_u.d_child, &dparent->d_subdirs); write_seqcount_end(&dentry->d_seq); @@ -2714,7 +2720,6 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) write_seqlock(&rename_lock); __d_materialise_dentry(dentry, new); write_sequnlock(&rename_lock); - __d_drop(new); _d_rehash(new); spin_unlock(&new->d_lock); spin_unlock(&inode->i_lock); @@ -2778,7 +2783,6 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode) * could splice into our tree? */ __d_materialise_dentry(dentry, alias); write_sequnlock(&rename_lock); - __d_drop(alias); goto found; } else { /* Nope, but we must(!) avoid directory -- cgit v1.2.3 From f5be3e29127aec8c87f883aadadff337f8c2cfd7 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sat, 13 Sep 2014 21:50:45 -0400 Subject: fix bogus read_seqretry() checks introduced in b37199e read_seqretry() returns true on mismatch, not on match... Cc: stable@vger.kernel.org # 3.15+ Signed-off-by: Al Viro --- fs/namei.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'fs') diff --git a/fs/namei.c b/fs/namei.c index a996bb48dfab..3d1dc745f9d8 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1137,7 +1137,7 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, */ *inode = path->dentry->d_inode; } - return read_seqretry(&mount_lock, nd->m_seq) && + return !read_seqretry(&mount_lock, nd->m_seq) && !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); } @@ -1174,7 +1174,7 @@ static int follow_dotdot_rcu(struct nameidata *nd) nd->path.mnt = &mounted->mnt; nd->path.dentry = mounted->mnt.mnt_root; nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); - if (!read_seqretry(&mount_lock, nd->m_seq)) + if (read_seqretry(&mount_lock, nd->m_seq)) goto failed; } nd->inode = nd->path.dentry->d_inode; -- cgit v1.2.3 From 7bd88377d482e1eae3c5329b12e33cfd664fa6a9 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sat, 13 Sep 2014 21:55:46 -0400 Subject: don't bugger nd->seq on set_root_rcu() from follow_dotdot_rcu() return the value instead, and have path_init() do the assignment. Broken by "vfs: Fix absolute RCU path walk failures due to uninitialized seq number", which was Cc-stable with 2.6.38+ as destination. This one should go where it went. To avoid dummy value returned in case when root is already set (it would do no harm, actually, since the only caller that doesn't ignore the return value is guaranteed to have nd->root *not* set, but it's more obvious that way), lift the check into callers. And do the same to set_root(), to keep them in sync. Cc: stable@vger.kernel.org # 2.6.38+ Signed-off-by: Al Viro --- fs/namei.c | 33 +++++++++++++++++---------------- 1 file changed, 17 insertions(+), 16 deletions(-) (limited to 'fs') diff --git a/fs/namei.c b/fs/namei.c index 3d1dc745f9d8..fe47e6d8e85f 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -643,24 +643,22 @@ static int complete_walk(struct nameidata *nd) static __always_inline void set_root(struct nameidata *nd) { - if (!nd->root.mnt) - get_fs_root(current->fs, &nd->root); + get_fs_root(current->fs, &nd->root); } static int link_path_walk(const char *, struct nameidata *); -static __always_inline void set_root_rcu(struct nameidata *nd) +static __always_inline unsigned set_root_rcu(struct nameidata *nd) { - if (!nd->root.mnt) { - struct fs_struct *fs = current->fs; - unsigned seq; + struct fs_struct *fs = current->fs; + unsigned seq, res; - do { - seq = read_seqcount_begin(&fs->seq); - nd->root = fs->root; - nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); - } while (read_seqcount_retry(&fs->seq, seq)); - } + do { + seq = read_seqcount_begin(&fs->seq); + nd->root = fs->root; + res = __read_seqcount_begin(&nd->root.dentry->d_seq); + } while (read_seqcount_retry(&fs->seq, seq)); + return res; } static void path_put_conditional(struct path *path, struct nameidata *nd) @@ -860,7 +858,8 @@ follow_link(struct path *link, struct nameidata *nd, void **p) return PTR_ERR(s); } if (*s == '/') { - set_root(nd); + if (!nd->root.mnt) + set_root(nd); path_put(&nd->path); nd->path = nd->root; path_get(&nd->root); @@ -1143,7 +1142,8 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, static int follow_dotdot_rcu(struct nameidata *nd) { - set_root_rcu(nd); + if (!nd->root.mnt) + set_root_rcu(nd); while (1) { if (nd->path.dentry == nd->root.dentry && @@ -1256,7 +1256,8 @@ static void follow_mount(struct path *path) static void follow_dotdot(struct nameidata *nd) { - set_root(nd); + if (!nd->root.mnt) + set_root(nd); while(1) { struct dentry *old = nd->path.dentry; @@ -1852,7 +1853,7 @@ static int path_init(int dfd, const char *name, unsigned int flags, if (*name=='/') { if (flags & LOOKUP_RCU) { rcu_read_lock(); - set_root_rcu(nd); + nd->seq = set_root_rcu(nd); } else { set_root(nd); path_get(&nd->root); -- cgit v1.2.3 From 4023bfc9f351a7994fb6a7d515476c320f94a574 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sat, 13 Sep 2014 21:59:43 -0400 Subject: be careful with nd->inode in path_init() and follow_dotdot_rcu() in the former we simply check if dentry is still valid after picking its ->d_inode; in the latter we fetch ->d_inode in the same places where we fetch dentry and its ->d_seq, under the same checks. Cc: stable@vger.kernel.org # 2.6.38+ Signed-off-by: Al Viro --- fs/namei.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) (limited to 'fs') diff --git a/fs/namei.c b/fs/namei.c index fe47e6d8e85f..d07bc1b206c3 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1142,6 +1142,7 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, static int follow_dotdot_rcu(struct nameidata *nd) { + struct inode *inode = nd->inode; if (!nd->root.mnt) set_root_rcu(nd); @@ -1155,6 +1156,7 @@ static int follow_dotdot_rcu(struct nameidata *nd) struct dentry *parent = old->d_parent; unsigned seq; + inode = parent->d_inode; seq = read_seqcount_begin(&parent->d_seq); if (read_seqcount_retry(&old->d_seq, nd->seq)) goto failed; @@ -1164,6 +1166,7 @@ static int follow_dotdot_rcu(struct nameidata *nd) } if (!follow_up_rcu(&nd->path)) break; + inode = nd->path.dentry->d_inode; nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); } while (d_mountpoint(nd->path.dentry)) { @@ -1173,11 +1176,12 @@ static int follow_dotdot_rcu(struct nameidata *nd) break; nd->path.mnt = &mounted->mnt; nd->path.dentry = mounted->mnt.mnt_root; + inode = nd->path.dentry->d_inode; nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); if (read_seqretry(&mount_lock, nd->m_seq)) goto failed; } - nd->inode = nd->path.dentry->d_inode; + nd->inode = inode; return 0; failed: @@ -1904,7 +1908,14 @@ static int path_init(int dfd, const char *name, unsigned int flags, } nd->inode = nd->path.dentry->d_inode; - return 0; + if (!(flags & LOOKUP_RCU)) + return 0; + if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) + return 0; + if (!(nd->flags & LOOKUP_ROOT)) + nd->root.mnt = NULL; + rcu_read_unlock(); + return -ECHILD; } static inline int lookup_last(struct nameidata *nd, struct path *path) -- cgit v1.2.3