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| author | Al Viro <viro@zeniv.linux.org.uk> | 2015-05-09 19:02:01 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2015-05-15 01:10:22 -0400 |
| commit | 8f47a0167c567de4ef552e26101b4f54a9b8ad48 (patch) | |
| tree | 90fb1b9cc84b9c3e2b51a918cdb140ab1a061218 /fs/namei.c | |
| parent | 8c1b456689ac0b27e8e16b35190e89a02fd1f121 (diff) | |
| download | lwn-8f47a0167c567de4ef552e26101b4f54a9b8ad48.tar.gz lwn-8f47a0167c567de4ef552e26101b4f54a9b8ad48.zip | |
namei: handle absolute symlinks without dropping out of RCU mode
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/namei.c')
| -rw-r--r-- | fs/namei.c | 31 |
1 files changed, 20 insertions, 11 deletions
diff --git a/fs/namei.c b/fs/namei.c index bf46e1010a74..a5ed0d070a20 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -499,7 +499,7 @@ struct nameidata { struct path root; struct inode *inode; /* path.dentry.d_inode */ unsigned int flags; - unsigned seq, m_seq; + unsigned seq, m_seq, root_seq; int last_type; unsigned depth; int total_link_count; @@ -788,14 +788,14 @@ static __always_inline void set_root(struct nameidata *nd) static __always_inline unsigned set_root_rcu(struct nameidata *nd) { struct fs_struct *fs = current->fs; - unsigned seq, res; + unsigned seq; do { seq = read_seqcount_begin(&fs->seq); nd->root = fs->root; - res = __read_seqcount_begin(&nd->root.dentry->d_seq); + nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); } while (read_seqcount_retry(&fs->seq, seq)); - return res; + return nd->root_seq; } static void path_put_conditional(struct path *path, struct nameidata *nd) @@ -995,15 +995,23 @@ const char *get_link(struct nameidata *nd) } if (*res == '/') { if (nd->flags & LOOKUP_RCU) { - if (unlikely(unlazy_walk(nd, NULL, 0))) + struct dentry *d; + if (!nd->root.mnt) + set_root_rcu(nd); + nd->path = nd->root; + d = nd->path.dentry; + nd->inode = d->d_inode; + nd->seq = nd->root_seq; + if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) return ERR_PTR(-ECHILD); + } else { + if (!nd->root.mnt) + set_root(nd); + path_put(&nd->path); + nd->path = nd->root; + path_get(&nd->root); + nd->inode = nd->path.dentry->d_inode; } - if (!nd->root.mnt) - set_root(nd); - path_put(&nd->path); - nd->path = nd->root; - path_get(&nd->root); - nd->inode = nd->path.dentry->d_inode; nd->flags |= LOOKUP_JUMPED; while (unlikely(*++res == '/')) ; @@ -1979,6 +1987,7 @@ static const char *path_init(int dfd, const struct filename *name, if (flags & LOOKUP_RCU) { rcu_read_lock(); nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); + nd->root_seq = nd->seq; nd->m_seq = read_seqbegin(&mount_lock); } else { path_get(&nd->path); |