lkml.org 
[lkml]   [2015]   [May]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH v3 109/110] namei: handle absolute symlinks without dropping out of RCU mode
    Date
    From: Al Viro <viro@zeniv.linux.org.uk>

    Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
    ---
    fs/namei.c | 30 +++++++++++++++++++-----------
    1 file changed, 19 insertions(+), 11 deletions(-)

    diff --git a/fs/namei.c b/fs/namei.c
    index 1771143..fc8df8b 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;
    @@ -780,14 +780,14 @@ 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)
    @@ -988,15 +988,23 @@ 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 == '/'))
    ;
    --
    2.1.4


    \
     
     \ /
      Last update: 2015-05-11 20:41    [W:4.394 / U:0.216 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site