From: Max Reitz <mreitz@redhat.com> To: qemu-devel@nongnu.org, virtio-fs@redhat.com Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>, Max Reitz <mreitz@redhat.com> Subject: [PATCH v2 2/9] virtiofsd: Use lo_inode_open() instead of openat() Date: Wed, 9 Jun 2021 17:55:44 +0200 [thread overview] Message-ID: <20210609155551.44437-3-mreitz@redhat.com> (raw) In-Reply-To: <20210609155551.44437-1-mreitz@redhat.com> 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 <mreitz@redhat.com> Reviewed-by: Connor Kuehl <ckuehl@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
WARNING: multiple messages have this Message-ID (diff)
From: Max Reitz <mreitz@redhat.com> To: qemu-devel@nongnu.org, virtio-fs@redhat.com Cc: Max Reitz <mreitz@redhat.com> Subject: [Virtio-fs] [PATCH v2 2/9] virtiofsd: Use lo_inode_open() instead of openat() Date: Wed, 9 Jun 2021 17:55:44 +0200 [thread overview] Message-ID: <20210609155551.44437-3-mreitz@redhat.com> (raw) In-Reply-To: <20210609155551.44437-1-mreitz@redhat.com> 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 <mreitz@redhat.com> Reviewed-by: Connor Kuehl <ckuehl@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
next prev parent reply other threads:[~2021-06-09 16:04 UTC|newest] Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-06-09 15:55 [PATCH v2 0/9] virtiofsd: Allow using file handles instead of O_PATH FDs Max Reitz 2021-06-09 15:55 ` [Virtio-fs] " Max Reitz 2021-06-09 15:55 ` [PATCH v2 1/9] virtiofsd: Add TempFd structure Max Reitz 2021-06-09 15:55 ` [Virtio-fs] " Max Reitz 2021-06-09 15:55 ` Max Reitz [this message] 2021-06-09 15:55 ` [Virtio-fs] [PATCH v2 2/9] virtiofsd: Use lo_inode_open() instead of openat() Max Reitz 2021-06-09 15:55 ` [PATCH v2 3/9] virtiofsd: Add lo_inode_fd() helper Max Reitz 2021-06-09 15:55 ` [Virtio-fs] " Max Reitz 2021-06-09 15:55 ` [PATCH v2 4/9] virtiofsd: Let lo_fd() return a TempFd Max Reitz 2021-06-09 15:55 ` [Virtio-fs] " Max Reitz 2021-06-09 15:55 ` [PATCH v2 5/9] virtiofsd: Let lo_inode_open() " Max Reitz 2021-06-09 15:55 ` [Virtio-fs] " Max Reitz 2021-06-09 15:55 ` [PATCH v2 6/9] virtiofsd: Add lo_inode.fhandle Max Reitz 2021-06-09 15:55 ` [Virtio-fs] " Max Reitz 2021-06-09 15:55 ` [PATCH v2 7/9] virtiofsd: Add inodes_by_handle hash table Max Reitz 2021-06-09 15:55 ` [Virtio-fs] " Max Reitz 2021-06-11 20:04 ` Vivek Goyal 2021-06-16 13:38 ` Max Reitz 2021-06-17 21:21 ` Vivek Goyal 2021-06-18 8:28 ` Max Reitz 2021-06-18 18:29 ` Vivek Goyal 2021-06-21 9:02 ` Max Reitz 2021-06-21 15:51 ` Vivek Goyal 2021-06-21 17:07 ` Max Reitz 2021-06-21 21:27 ` Vivek Goyal 2021-07-13 15:07 ` Max Reitz 2021-07-20 14:50 ` Vivek Goyal 2021-07-21 8:29 ` Max Reitz 2021-06-18 8:30 ` Max Reitz 2021-06-18 8:30 ` [Virtio-fs] " Max Reitz 2021-06-09 15:55 ` [PATCH v2 8/9] virtiofsd: Optionally fill lo_inode.fhandle Max Reitz 2021-06-09 15:55 ` [Virtio-fs] " Max Reitz 2021-06-09 15:55 ` [PATCH v2 9/9] virtiofsd: Add lazy lo_do_find() Max Reitz 2021-06-09 15:55 ` [Virtio-fs] " Max Reitz 2021-06-11 19:19 ` [PATCH v2 0/9] virtiofsd: Allow using file handles instead of O_PATH FDs Vivek Goyal 2021-06-11 19:19 ` [Virtio-fs] " Vivek Goyal 2021-06-16 13:41 ` Max Reitz 2021-06-16 13:41 ` [Virtio-fs] " Max Reitz
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