| Message ID | 20210928123730.393551-2-nborisov@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/2] btrfs-progs: Ignore path device during device scan | expand |
On Tue, Sep 28, 2021 at 03:37:30PM +0300, Nikolay Borisov wrote: > @@ -372,23 +373,56 @@ void free_seen_fsid(struct seen_fsid *seen_fsid_hash[]) > } > } > > -#ifdef HAVE_LIBUDEV > -static bool is_path_device(char *device_path) > +#ifdef STATIC_BUILD > +static bool __is_path_device(dev_t dev) > +{ > + FILE *file; > + char *line = NULL; > + size_t len = 0; > + ssize_t nread; > + bool ret = false; > + int ret2; > + struct stat dev_stat; > + char path[100]; char path[PATH_MAX]; No arbitrary constants please. For paths always use a full buffer size, though in this case it's not strictly necessary. > + > + ret2 = snprintf(path, 100, "/run/udev/data/b%u:%u", major(dev_stat.st_rdev), > + minor(dev_stat.st_rdev)); > + > + if (ret2 >= 100 || ret2 < 0) So >= 100 never happens and with PATH_MAX you can drop the part of the condition as well. > + return false; > + > + file = fopen(path, "r"); > + if (file == NULL) > + return false; > + > + while ((nread = getline(&line, &len, file)) != -1) { > + if (strstr(line, "DM_MULTIPATH_DEVICE_PATH=1")) { So this is peeking into udev internal files but I like that you do strstr, that sounds future proof enough for a fallback. > + ret = true; > + printf("found dm multipath line: %s\n", line); Is this a debugging print? We have the pr_verbose helper that takes a level of verbosity so for debugging you can do pr_verbose(3, "..."). This hasnt' been used much but messages used for developing a feature and making sure it works as expected can be turned into high verbose level messages for free and one day it becomes useful. > + break; > + } > + } > + > + if (line) > + free(line); > + > + fclose(file); > + > + return ret; > +} > +#elif defined(HAVE_LIBUDEV) > +static bool __is_path_device(dev_t device) Please avoid functions with __, also s/path/multipath/ would be much more clear. > { > struct udev *udev = NULL; > struct udev_device *dev = NULL; > - struct stat dev_stat; > const char *val; > bool ret = false; > > - if (stat(device_path, &dev_stat) < 0) > - return false; > - > udev = udev_new(); > if (!udev) > goto out; > > - dev = udev_device_new_from_devnum(udev, 'b', dev_stat.st_rdev); > + dev = udev_device_new_from_devnum(udev, 'b', device); > if (!dev) > goto out; > > @@ -401,8 +435,24 @@ static bool is_path_device(char *device_path) > > return ret; > } > +#else > +static bool __is_path_device(dev_t device) > +{ > + return false; > +} > #endif > > +static bool is_path_device(char *device_path) > +{ > + struct stat dev_stat; > + > + if (stat(device_path, &dev_stat) < 0) > + return false; > + > + return __is_path_device(dev_stat.st_rdev); > + > +} > + > int btrfs_scan_devices(int verbose) > { > int fd = -1; > @@ -433,10 +483,8 @@ int btrfs_scan_devices(int verbose) > /* if we are here its definitely a btrfs disk*/ > strncpy_null(path, blkid_dev_devname(dev)); > > -#ifdef HAVE_LIBUDEV > if (is_path_device(path)) > continue; > -#endif > > fd = open(path, O_RDONLY); > if (fd < 0) { > -- > 2.17.1
diff --git a/common/device-scan.c b/common/device-scan.c index 2ed0e34d3664..9779dd1aedf3 100644 --- a/common/device-scan.c +++ b/common/device-scan.c @@ -29,6 +29,7 @@ #include <dirent.h> #include <blkid/blkid.h> #include <uuid/uuid.h> +#include <sys/sysmacros.h> #ifdef HAVE_LIBUDEV #include <sys/stat.h> #include <libudev.h> @@ -372,23 +373,56 @@ void free_seen_fsid(struct seen_fsid *seen_fsid_hash[]) } } -#ifdef HAVE_LIBUDEV -static bool is_path_device(char *device_path) +#ifdef STATIC_BUILD +static bool __is_path_device(dev_t dev) +{ + FILE *file; + char *line = NULL; + size_t len = 0; + ssize_t nread; + bool ret = false; + int ret2; + struct stat dev_stat; + char path[100]; + + ret2 = snprintf(path, 100, "/run/udev/data/b%u:%u", major(dev_stat.st_rdev), + minor(dev_stat.st_rdev)); + + if (ret2 >= 100 || ret2 < 0) + return false; + + file = fopen(path, "r"); + if (file == NULL) + return false; + + while ((nread = getline(&line, &len, file)) != -1) { + if (strstr(line, "DM_MULTIPATH_DEVICE_PATH=1")) { + ret = true; + printf("found dm multipath line: %s\n", line); + break; + } + } + + if (line) + free(line); + + fclose(file); + + return ret; +} +#elif defined(HAVE_LIBUDEV) +static bool __is_path_device(dev_t device) { struct udev *udev = NULL; struct udev_device *dev = NULL; - struct stat dev_stat; const char *val; bool ret = false; - if (stat(device_path, &dev_stat) < 0) - return false; - udev = udev_new(); if (!udev) goto out; - dev = udev_device_new_from_devnum(udev, 'b', dev_stat.st_rdev); + dev = udev_device_new_from_devnum(udev, 'b', device); if (!dev) goto out; @@ -401,8 +435,24 @@ static bool is_path_device(char *device_path) return ret; } +#else +static bool __is_path_device(dev_t device) +{ + return false; +} #endif +static bool is_path_device(char *device_path) +{ + struct stat dev_stat; + + if (stat(device_path, &dev_stat) < 0) + return false; + + return __is_path_device(dev_stat.st_rdev); + +} + int btrfs_scan_devices(int verbose) { int fd = -1; @@ -433,10 +483,8 @@ int btrfs_scan_devices(int verbose) /* if we are here its definitely a btrfs disk*/ strncpy_null(path, blkid_dev_devname(dev)); -#ifdef HAVE_LIBUDEV if (is_path_device(path)) continue; -#endif fd = open(path, O_RDONLY); if (fd < 0) {
Since libudev doesn't provide a static version of the library for static build btrfs-progs will have to provide manual fallback. THis change does exactly this by parsing the udev database files hosted /run/udev/data/. Under that directory every block device should have a file with the following name: bMAJ:MIN. So implement the bare minimum code necessary to parse this file and search for the presence of DM_MULTIPATH_DEVICE_PATH udev attribute. This could likely be racy since access to the udev database is done outside of libudev but that's the best that can be done when implementing this manually. To reduce duplication of code also factor out the specifics of is_path_device to __is_path_device which will contain the appropriate implementation according to the build mode (i.e relying on libudev in case of normal build or manual fall back code in case of static build) or simply utilize the old logic (in case of a normal build and libudev missing). Signed-off-by: Nikolay Borisov <nborisov@suse.com> --- common/device-scan.c | 66 ++++++++++++++++++++++++++++++++++++++------ 1 file changed, 57 insertions(+), 9 deletions(-)