The xattr functions want a non-O_PATH FD, so they reopen the lo_inode.fd with the flags they need through /proc/self/fd.
Similarly, lo_opendir() needs an O_RDONLY FD. Instead of the /proc/self/fd trick, it just uses openat(fd, "."), because the FD is guaranteed to be a directory, so this works. All cases have one problem in common, though: In the future, when we may have a file handle in the lo_inode instead of an FD, querying an lo_inode FD may incur an open_by_handle_at() call. It does not make sense to then reopen that FD with custom flags, those should have been passed to open_by_handle_at() instead. Use lo_inode_open() instead of openat(). As part of the file handle change, lo_inode_open() will be made to invoke openat() only if lo_inode.fd is valid. Otherwise, it will invoke open_by_handle_at() with the right flags from the start. Consequently, after this patch, lo_inode_open() is the only place to invoke openat() to reopen an existing FD with different flags. Signed-off-by: Max Reitz <mre...@redhat.com> Reviewed-by: Connor Kuehl <cku...@redhat.com> --- tools/virtiofsd/passthrough_ll.c | 43 ++++++++++++++++++++------------ 1 file changed, 27 insertions(+), 16 deletions(-) diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index a4674aba80..436f771d2a 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -1645,18 +1645,26 @@ static void lo_opendir(fuse_req_t req, fuse_ino_t ino, { int error = ENOMEM; struct lo_data *lo = lo_data(req); - struct lo_dirp *d; + struct lo_inode *inode; + struct lo_dirp *d = NULL; int fd; ssize_t fh; + inode = lo_inode(req, ino); + if (!inode) { + error = EBADF; + goto out_err; + } + d = calloc(1, sizeof(struct lo_dirp)); if (d == NULL) { goto out_err; } - fd = openat(lo_fd(req, ino), ".", O_RDONLY); - if (fd == -1) { - goto out_errno; + fd = lo_inode_open(lo, inode, O_RDONLY); + if (fd < 0) { + error = -fd; + goto out_err; } d->dp = fdopendir(fd); @@ -1685,6 +1693,7 @@ static void lo_opendir(fuse_req_t req, fuse_ino_t ino, out_errno: error = errno; out_err: + lo_inode_put(lo, &inode); if (d) { if (d->dp) { closedir(d->dp); @@ -2827,7 +2836,6 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name, } } - sprintf(procname, "%i", inode->fd); /* * It is not safe to open() non-regular/non-dir files in file server * unless O_PATH is used, so use that method for regular files/dir @@ -2835,12 +2843,14 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name, * Otherwise, call fchdir() to avoid open(). */ if (S_ISREG(inode->filetype) || S_ISDIR(inode->filetype)) { - fd = openat(lo->proc_self_fd, procname, O_RDONLY); + fd = lo_inode_open(lo, inode, O_RDONLY); if (fd < 0) { - goto out_err; + saverr = -fd; + goto out; } ret = fgetxattr(fd, name, value, size); } else { + sprintf(procname, "%i", inode->fd); /* fchdir should not fail here */ FCHDIR_NOFAIL(lo->proc_self_fd); ret = getxattr(procname, name, value, size); @@ -2906,14 +2916,15 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size) } } - sprintf(procname, "%i", inode->fd); if (S_ISREG(inode->filetype) || S_ISDIR(inode->filetype)) { - fd = openat(lo->proc_self_fd, procname, O_RDONLY); + fd = lo_inode_open(lo, inode, O_RDONLY); if (fd < 0) { - goto out_err; + saverr = -fd; + goto out; } ret = flistxattr(fd, value, size); } else { + sprintf(procname, "%i", inode->fd); /* fchdir should not fail here */ FCHDIR_NOFAIL(lo->proc_self_fd); ret = listxattr(procname, value, size); @@ -3039,15 +3050,15 @@ static void lo_setxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name, fuse_log(FUSE_LOG_DEBUG, "lo_setxattr(ino=%" PRIu64 ", name=%s value=%s size=%zd)\n", ino, name, value, size); - sprintf(procname, "%i", inode->fd); if (S_ISREG(inode->filetype) || S_ISDIR(inode->filetype)) { - fd = openat(lo->proc_self_fd, procname, O_RDONLY); + fd = lo_inode_open(lo, inode, O_RDONLY); if (fd < 0) { - saverr = errno; + saverr = -fd; goto out; } ret = fsetxattr(fd, name, value, size, flags); } else { + sprintf(procname, "%i", inode->fd); /* fchdir should not fail here */ FCHDIR_NOFAIL(lo->proc_self_fd); ret = setxattr(procname, name, value, size, flags); @@ -3105,15 +3116,15 @@ static void lo_removexattr(fuse_req_t req, fuse_ino_t ino, const char *in_name) fuse_log(FUSE_LOG_DEBUG, "lo_removexattr(ino=%" PRIu64 ", name=%s)\n", ino, name); - sprintf(procname, "%i", inode->fd); if (S_ISREG(inode->filetype) || S_ISDIR(inode->filetype)) { - fd = openat(lo->proc_self_fd, procname, O_RDONLY); + fd = lo_inode_open(lo, inode, O_RDONLY); if (fd < 0) { - saverr = errno; + saverr = -fd; goto out; } ret = fremovexattr(fd, name); } else { + sprintf(procname, "%i", inode->fd); /* fchdir should not fail here */ FCHDIR_NOFAIL(lo->proc_self_fd); ret = removexattr(procname, name); -- 2.31.1