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author | Karel Zak | 2010-12-01 14:04:35 +0100 |
---|---|---|
committer | Karel Zak | 2010-12-01 14:04:35 +0100 |
commit | b61e939013282d8da2fbc2dc60c2cb4e58b8ab17 (patch) | |
tree | 12ccaa865bde2b30c138bcd974f530979404cb31 /mount/lomount.c | |
parent | lscpu: use GPLv2+ (diff) | |
download | kernel-qcow2-util-linux-b61e939013282d8da2fbc2dc60c2cb4e58b8ab17.tar.gz kernel-qcow2-util-linux-b61e939013282d8da2fbc2dc60c2cb4e58b8ab17.tar.xz kernel-qcow2-util-linux-b61e939013282d8da2fbc2dc60c2cb4e58b8ab17.zip |
losetup: use /sys/dev/block/.../loop/backing_file
The basic loopdev attributes are available in sysfs since kernel
2.6.37. This patch uses the backing_file attribute from sysfs for very
long filenames (the LOOP_GET_STATUS ioctl uses only 64 bytes for the
filename).
old version:
# losetup -a
/dev/loop0: [0804]:12865322 (/home/images/filesystems/this_is_really_really_long_directory_*)
new version:
# losetup -a
/dev/loop0: [0804]:12865322 (/home/images/filesystems/this_is_really_really_long_directory_name/ext2.img)
Signed-off-by: Karel Zak <kzak@redhat.com>
Diffstat (limited to 'mount/lomount.c')
-rw-r--r-- | mount/lomount.c | 44 |
1 files changed, 43 insertions, 1 deletions
diff --git a/mount/lomount.c b/mount/lomount.c index d6556fc71..90149536a 100644 --- a/mount/lomount.c +++ b/mount/lomount.c @@ -80,6 +80,35 @@ struct looplist { #define LLFLG_SUBDIR (1 << 5) /* /dev/loop/N */ #define LLFLG_DFLT (1 << 6) /* directly try to check default loops */ +/* TODO: move to lib/sysfs.c */ +static char *loopfile_from_sysfs(const char *device) +{ + FILE *f; + struct stat st; + char buf[PATH_MAX], *res = NULL; + + if (stat(device, &st) || !S_ISBLK(st.st_mode)) + return NULL; + + snprintf(buf, sizeof(buf), _PATH_SYS_DEVBLOCK "/%d:%d/loop/backing_file", + major(st.st_rdev), minor(st.st_rdev)); + + f = fopen(buf, "r"); + if (!f) + return NULL; + + if (fgets(buf, sizeof(buf), f)) { + size_t sz = strlen(buf); + if (sz) { + buf[sz - 1] = '\0'; + res = xstrdup(buf); + } + } + + fclose(f); + return res; +} + int is_loop_device (const char *device) { struct stat st; @@ -379,13 +408,26 @@ show_loop_fd(int fd, char *device) { if (ioctl(fd, LOOP_GET_STATUS64, &loopinfo64) == 0) { + char *lofile = NULL; + loopinfo64.lo_file_name[LO_NAME_SIZE-2] = '*'; loopinfo64.lo_file_name[LO_NAME_SIZE-1] = 0; loopinfo64.lo_crypt_name[LO_NAME_SIZE-1] = 0; + /* ioctl has limited buffer for backing file name, since + * kernel 2.6.37 the filename is available in sysfs too + */ + if (strlen((char *) loopinfo64.lo_file_name) == LO_NAME_SIZE - 1) + lofile = loopfile_from_sysfs(device); + if (!lofile) + lofile = (char *) loopinfo64.lo_file_name; + printf("%s: [%04" PRIx64 "]:%" PRIu64 " (%s)", device, loopinfo64.lo_device, loopinfo64.lo_inode, - loopinfo64.lo_file_name); + lofile); + + if (lofile != (char *) loopinfo64.lo_file_name) + free(lofile); if (loopinfo64.lo_offset) printf(_(", offset %" PRIu64 ), loopinfo64.lo_offset); |