[PATCH 32/39] union-mount: Implement union-aware writable open()
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From: Valerie Aurora on 8 Aug 2010 12:00 Copy up a file when opened with write permissions. Does not copy up the file data when O_TRUNC is specified. Signed-off-by: Valerie Aurora <vaurora(a)redhat.com> --- fs/namei.c | 28 ++++++++++++++++++++++++++++ 1 files changed, 28 insertions(+), 0 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index 67ebf4a..88d1a79 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1911,6 +1911,24 @@ exit: return ERR_PTR(error); } +static int open_union_copyup(struct nameidata *nd, struct path *path, + int open_flag) +{ + struct vfsmount *oldmnt = path->mnt; + int error; + + if (open_flag & O_TRUNC) + error = union_copyup_len(nd, path, 0); + else + error = union_copyup(nd, path); + if (error) + return error; + if (oldmnt != path->mnt) + mntput(nd->path.mnt); + + return error; +} + static struct file *do_last(struct nameidata *nd, struct path *path, int open_flag, int acc_mode, int mode, const char *pathname) @@ -1962,6 +1980,11 @@ static struct file *do_last(struct nameidata *nd, struct path *path, if (!path->dentry->d_inode->i_op->lookup) goto exit_dput; } + if (acc_mode & MAY_WRITE) { + error = open_union_copyup(nd, path, open_flag); + if (error) + goto exit_dput; + } path_to_nameidata(path, nd); audit_inode(pathname, nd->path.dentry); goto ok; @@ -2033,6 +2056,11 @@ static struct file *do_last(struct nameidata *nd, struct path *path, if (path->dentry->d_inode->i_op->follow_link) return NULL; + if (acc_mode & MAY_WRITE) { + error = open_union_copyup(nd, path, open_flag); + if (error) + goto exit_dput; + } path_to_nameidata(path, nd); error = -EISDIR; if (S_ISDIR(path->dentry->d_inode->i_mode)) -- 1.6.3.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |