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    Subject[PATCH v3 106/110] namei: don't unlazy until get_link()
    Date
    From: Al Viro <viro@zeniv.linux.org.uk>

    Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
    ---
    fs/namei.c | 37 ++++++++++++++++++++++++++-----------
    1 file changed, 26 insertions(+), 11 deletions(-)

    diff --git a/fs/namei.c b/fs/namei.c
    index 090214b..4d6065d 100644
    --- a/fs/namei.c
    +++ b/fs/namei.c
    @@ -536,10 +536,19 @@ static void restore_nameidata(struct nameidata *old)

    static int __nd_alloc_stack(struct nameidata *nd)
    {
    - struct saved *p = kmalloc(MAXSYMLINKS * sizeof(struct saved),
    + struct saved *p;
    +
    + if (nd->flags & LOOKUP_RCU) {
    + p= kmalloc(MAXSYMLINKS * sizeof(struct saved),
    + GFP_ATOMIC);
    + if (unlikely(!p))
    + return -ECHILD;
    + } else {
    + p= kmalloc(MAXSYMLINKS * sizeof(struct saved),
    GFP_KERNEL);
    - if (unlikely(!p))
    - return -ENOMEM;
    + if (unlikely(!p))
    + return -ENOMEM;
    + }
    memcpy(p, nd->internal, sizeof(nd->internal));
    nd->stack = p;
    return 0;
    @@ -949,8 +958,10 @@ const char *get_link(struct nameidata *nd)
    int error;
    const char *res;

    - BUG_ON(nd->flags & LOOKUP_RCU);
    -
    + if (nd->flags & LOOKUP_RCU) {
    + if (unlikely(unlazy_walk(nd, NULL, 0)))
    + return ERR_PTR(-ECHILD);
    + }
    cond_resched();

    touch_atime(&last->link);
    @@ -1632,17 +1643,21 @@ static int pick_link(struct nameidata *nd, struct path *link,
    path_to_nameidata(link, nd);
    return -ELOOP;
    }
    - if (nd->flags & LOOKUP_RCU) {
    - if (unlikely(unlazy_link(nd, link, seq)))
    - return -ECHILD;
    - } else {
    + if (!(nd->flags & LOOKUP_RCU)) {
    if (link->mnt == nd->path.mnt)
    mntget(link->mnt);
    }
    error = nd_alloc_stack(nd);
    if (unlikely(error)) {
    - path_put(link);
    - return error;
    + if (error == -ECHILD) {
    + if (unlikely(unlazy_link(nd, link, seq)))
    + return -ECHILD;
    + error = nd_alloc_stack(nd);
    + }
    + if (error) {
    + path_put(link);
    + return error;
    + }
    }

    last = nd->stack + nd->depth++;
    --
    2.1.4


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