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    Subject[PATCH v5 03/19] vfs: make fstatat retry on ESTALE errors from getattr call
    Date
    Signed-off-by: Jeff Layton <jlayton@redhat.com>
    ---
    fs/namei.c | 2 +-
    fs/stat.c | 21 ++++++++++++++++-----
    include/linux/fs.h | 1 +
    3 files changed, 18 insertions(+), 6 deletions(-)

    diff --git a/fs/namei.c b/fs/namei.c
    index 83a6f46..e66161f 100644
    --- a/fs/namei.c
    +++ b/fs/namei.c
    @@ -117,7 +117,7 @@
    * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
    * PATH_MAX includes the nul terminator --RR.
    */
    -static char *getname_flags(const char __user *filename, int flags, int *empty)
    +char *getname_flags(const char __user *filename, int flags, int *empty)
    {
    char *result = __getname(), *err;
    int len;
    diff --git a/fs/stat.c b/fs/stat.c
    index b6ff118..5afeb37 100644
    --- a/fs/stat.c
    +++ b/fs/stat.c
    @@ -72,9 +72,11 @@ EXPORT_SYMBOL(vfs_fstat);
    int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
    int flag)
    {
    + char *name;
    struct path path;
    int error = -EINVAL;
    - int lookup_flags = 0;
    + unsigned int try = 0;
    + unsigned int lookup_flags = 0;

    if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
    AT_EMPTY_PATH)) != 0)
    @@ -85,12 +87,21 @@ int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
    if (flag & AT_EMPTY_PATH)
    lookup_flags |= LOOKUP_EMPTY;

    - error = user_path_at(dfd, filename, lookup_flags, &path);
    - if (error)
    + name = getname_flags(filename, lookup_flags, NULL);
    + if (IS_ERR(name)) {
    + error = PTR_ERR(name);
    goto out;
    + }
    + do {
    + error = kern_path_at(dfd, name, lookup_flags, &path);
    + if (error)
    + break;

    - error = vfs_getattr(path.mnt, path.dentry, stat);
    - path_put(&path);
    + error = vfs_getattr(path.mnt, path.dentry, stat);
    + path_put(&path);
    + lookup_flags |= LOOKUP_REVAL;
    + } while (retry_estale(error, try++));
    + putname(name);
    out:
    return error;
    }
    diff --git a/include/linux/fs.h b/include/linux/fs.h
    index b776a97..f2e7371 100644
    --- a/include/linux/fs.h
    +++ b/include/linux/fs.h
    @@ -2201,6 +2201,7 @@ extern struct file *file_open_root(struct dentry *, struct vfsmount *,
    const char *, int);
    extern struct file * dentry_open(const struct path *, int, const struct cred *);
    extern int filp_close(struct file *, fl_owner_t id);
    +extern char *getname_flags(const char __user *, int, int *);
    extern char * getname(const char __user *);
    enum {
    FILE_CREATED = 1,
    --
    1.7.11.2


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