Originally reported on linux-btrfs list: http://www.mail-archive.com/linux-btrfs@xxxxxxxxxxxxxxx/msg08086.html Fix suggested on: http://www.mail-archive.com/linux-btrfs@xxxxxxxxxxxxxxx/msg08386.html loop_info.lo_name is limited to LO_NAME_SIZE (curerently 64) characters. This can cause a problem if a file whose full path is longer than LO_NAME_SIZE is currently mounted. This patch changes resolve_loop_device() to: * Check /sys/block/loopX/loop/backing_file first * If that fails, fallback to original behaviour using loop_info.lo_name Patch is both inline and attached (in case mail client mungles it). Signed-off-by: Fajar A. Nugraha <github@xxxxxxxxx> --- utils.c | 18 +++++++++++++++++- 1 files changed, 17 insertions(+), 1 deletions(-) diff --git a/utils.c b/utils.c index 178d1b9..a62eeee 100644 --- a/utils.c +++ b/utils.c @@ -649,6 +649,9 @@ int resolve_loop_device(const char* loop_dev, char* loop_file, int max_len) { int loop_fd; int ret_ioctl; + int sysfs_fd; + char sysfs_path[PATH_MAX]; + const char* sysfs_path_format = "/sys/block/loop%d/loop/backing_file"; struct loop_info loopinfo; if ((loop_fd = open(loop_dev, O_RDONLY)) < 0) @@ -658,7 +661,20 @@ int resolve_loop_device(const char* loop_dev, char* loop_file, int max_len) close(loop_fd); if (ret_ioctl == 0) - strncpy(loop_file, loopinfo.lo_name, max_len); + { + snprintf(sysfs_path, PATH_MAX, sysfs_path_format, loopinfo.lo_number); + sysfs_fd = open(sysfs_path, O_RDONLY); + if (sysfs_fd < 0) + { + strncpy(loop_file, loopinfo.lo_name, max_len); + } + else + { + read(sysfs_fd, loop_file, max_len); + loop_file[strlen(loop_file)-1] = '\0'; + close(sysfs_fd); + } + } else return -errno; -- 1.7.9
From e004166d8f3b30e0d498df995ac9de8b11cce59a Mon Sep 17 00:00:00 2001 From: "Fajar A. Nugraha" <github@xxxxxxxxx> Date: Thu, 23 Feb 2012 13:28:33 +0700 Subject: [PATCH] Fix incorrect "error checking ... mount status" in mkfs.btrfs Originally reported on linux-btrfs list: http://www.mail-archive.com/linux-btrfs@xxxxxxxxxxxxxxx/msg08086.html Fix suggested on: http://www.mail-archive.com/linux-btrfs@xxxxxxxxxxxxxxx/msg08386.html loop_info.lo_name is limited to LO_NAME_SIZE (curerently 64) characters. This can cause a problem if a file whose full path is longer than LO_NAME_SIZE is currently mounted. This patch changes resolve_loop_device() to: * Check /sys/block/loopX/loop/backing_file first * If that fails, fallback to original behaviour using loop_info.lo_name Signed-off-by: Fajar A. Nugraha <github@xxxxxxxxx> --- utils.c | 18 +++++++++++++++++- 1 files changed, 17 insertions(+), 1 deletions(-) diff --git a/utils.c b/utils.c index 178d1b9..a62eeee 100644 --- a/utils.c +++ b/utils.c @@ -649,6 +649,9 @@ int resolve_loop_device(const char* loop_dev, char* loop_file, int max_len) { int loop_fd; int ret_ioctl; + int sysfs_fd; + char sysfs_path[PATH_MAX]; + const char* sysfs_path_format = "/sys/block/loop%d/loop/backing_file"; struct loop_info loopinfo; if ((loop_fd = open(loop_dev, O_RDONLY)) < 0) @@ -658,7 +661,20 @@ int resolve_loop_device(const char* loop_dev, char* loop_file, int max_len) close(loop_fd); if (ret_ioctl == 0) - strncpy(loop_file, loopinfo.lo_name, max_len); + { + snprintf(sysfs_path, PATH_MAX, sysfs_path_format, loopinfo.lo_number); + sysfs_fd = open(sysfs_path, O_RDONLY); + if (sysfs_fd < 0) + { + strncpy(loop_file, loopinfo.lo_name, max_len); + } + else + { + read(sysfs_fd, loop_file, max_len); + loop_file[strlen(loop_file)-1] = '\0'; + close(sysfs_fd); + } + } else return -errno; -- 1.7.9
