[LTP] [PATCH 0/2] tst_find_backing_dev: fix stat fails /dev/root

[Alessandro Carminati]

This tst_find_backing_dev patch version adds support for btrfs
filesystems.
Strategy here is to understand if the subject is btrfs or not.
btrfs uses virtual device, and the major is 0. In all other test
supported file systems the major is always non zero.

If non btrfs it proceed as the previous version using sysfs minor
and major.
If btrfs it uses the BTRFS_IOC_FS_INFO ioctl to get it FS uuid.

non btrfs:
----------------------------------------------------------------
EXT4-fs (sda): re-mounted. Opts: (null). Quota mode: none.
Welcome to Buildroot
buildroot login: root
# /usr/lib/ltp-testsuite/testcases/bin/ioctl_loop05
tst_test.c:1363: TINFO: Timeout per run is 0h 05m 00s
tst_test.c:1115: TINFO: ext2/ext3/ext4 is supported by the test
tst_device.c:90: TINFO: Found free device 0 '/dev/loop0'
loop0: detected capacity change from 0 to 2048
tst_device.c:579: TINFO: Device numbers: 8/0
tst_device.c:611: TINFO: Use uevent strategy
ioctl_loop05.c:126: TINFO: backing dev(/dev/sda) logical_block_size is 512
ioctl_loop05.c:62: TINFO: Without setting lo_offset or sizelimit
ioctl_loop05.c:45: TINFO: In dio mode
ioctl_loop05.c:48: TPASS: lo_flags has LO_FLAGS_DIRECT_IO flag
ioctl_loop05.c:52: TPASS: /sys/block/loop0/loop/dio = 1
ioctl_loop05.c:45: TINFO: In non dio mode
ioctl_loop05.c:50: TPASS: lo_flags doesn't have LO_FLAGS_DIRECT_IO flag
ioctl_loop05.c:52: TPASS: /sys/block/loop0/loop/dio = 0
ioctl_loop05.c:69: TINFO: With offset equal to logical_block_size
loop0: detected capacity change from 2048 to 2047
ioctl_loop05.c:74: TPASS: LOOP_SET_DIRECT_IO succeeded
ioctl_loop05.c:45: TINFO: In dio mode
ioctl_loop05.c:48: TPASS: lo_flags has LO_FLAGS_DIRECT_IO flag
ioctl_loop05.c:52: TPASS: /sys/block/loop0/loop/dio = 1
ioctl_loop05.c:81: TINFO: With nonzero offset less than logical_block_size
ioctl_loop05.c:92: TPASS: LOOP_SET_DIRECT_IO failed as expected: EINVAL (22)

Summary:
passed   8
failed   0
broken   0
skipped  0
warnings 0
#

btrfs
----------------------------------------------------------------
BTRFS info (device sda): disk space caching is enabled
Welcome to Buildroot
buildroot login: root
# /usr/lib/ltp-testsuite/testcases/bin/ioctl_loop05
tst_test.c:1363: TINFO: Timeout per run is 0h 05m 00s
tst_test.c:1115: TINFO: btrfs is supported by the test
tst_device.c:90: TINFO: Found free device 0 '/dev/loop0'
loop0: detected capacity change from 0 to 2048
tst_device.c:579: TINFO: Device numbers: 0/15
tst_device.c:582: TINFO: Use BTRFS specific strategy
ioctl_loop05.c:126: TINFO: backing dev(/dev/sda) logical_block_size is 512
ioctl_loop05.c:62: TINFO: Without setting lo_offset or sizelimit
ioctl_loop05.c:45: TINFO: In dio mode
ioctl_loop05.c:48: TPASS: lo_flags has LO_FLAGS_DIRECT_IO flag
ioctl_loop05.c:52: TPASS: /sys/block/loop0/loop/dio = 1
ioctl_loop05.c:45: TINFO: In non dio mode
ioctl_loop05.c:50: TPASS: lo_flags doesn't have LO_FLAGS_DIRECT_IO flag
ioctl_loop05.c:52: TPASS: /sys/block/loop0/loop/dio = 0
ioctl_loop05.c:69: TINFO: With offset equal to logical_block_size
loop0: detected capacity change from 2048 to 2047
ioctl_loop05.c:74: TPASS: LOOP_SET_DIRECT_IO succeeded
ioctl_loop05.c:45: TINFO: In dio mode
ioctl_loop05.c:48: TPASS: lo_flags has LO_FLAGS_DIRECT_IO flag
ioctl_loop05.c:52: TPASS: /sys/block/loop0/loop/dio = 1
ioctl_loop05.c:81: TINFO: With nonzero offset less than logical_block_size
ioctl_loop05.c:87: TPASS: LOOP_SET_DIRECT_IO succeeded, offset is ignored

Summary:
passed   8
failed   0
broken   0
skipped  0
warnings 0
#

Alessandro Carminati (2):
  tst_find_backing_dev: Get dev name from /sys/dev/block/*/uevent
  c-test-api: Documentation updated

 doc/c-test-api.txt |  7 ++--
 lib/tst_device.c   | 86 ++++++++++++++++++++++++++++++----------------
 2 files changed, 62 insertions(+), 31 deletions(-)

-- 
2.34.1