[LU-11656] "lfs getstripe" on directory does not show default root layout

• Type: Bug
• Resolution: Fixed
• Priority: Major
• Fix Version/s: Lustre 2.14.0, Lustre 2.12.4
• Affects Version/s: Lustre 2.12.0, Lustre 2.10.8
• Severity: 3
• Assignee: Jian Yu
• Reporter: Andreas Dilger

Description

Running "lfs getstripe" on a directory only shows the simple filesystem default layout and not the root default layout that will actually be inherited by new files.

# lfs setstripe -p ssd /mnt/testfs
# lfs getstripe -d /mnt/testfs
stripe_count: 1 stripe_size: 1048576 stripe_offset: -1 pool: ssd
# mkdir /mnt/testfs/tmp/should_be_old
# lfs getstripe -d /mnt/testfs/tmp/should_be_old
stripe_count: 1 stripe_size: 1048576 stripe_offset: -1

Issue Links

• is blocking: LU-11918 Allow setting default file layout on root directory at mkfs time
• is related to: LU-12643 PFL layout don't inherit correctly from default layout.
• is related to: LU-13687 interop: "lfs find" prints spurious "No such file or directory" error messages
• is related to: LU-9982 Clients striping from mapped FID in nodemap
• is related to: LU-11739 Don't inherit default layout from root for new subdirectories

Comments

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/37072/
Subject: LU-11656 llite: fetch default layout for a directory
Project: fs/lustre-release
Branch: b2_12
Current Patch Set:
Commit: ca373442fc15a6dc77dcce36e91847c58ac45c03

[Gerrit Updater]

Minh Diep ([e-mail]) uploaded a new patch: https://review.whamcloud.com/37072
Subject: LU-11656 llite: fetch default layout for a directory
Project: fs/lustre-release
Branch: b2_12
Current Patch Set: 1
Commit: b4a8724c893ab66d4343dc68fbd00ebd1d561a32

[Peter Jones]

Landed for 2.14

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/36609/
Subject: LU-11656 llite: fetch default layout for a directory
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 3e8fa8a7396cd029cb0d7714a324343eed7f535e

[Gerrit Updater]

Jian Yu ([e-mail]) uploaded a new patch: https://review.whamcloud.com/36609
Subject: LU-11656 utils: fix "lfs getstripe" to fetch default layout for a directory
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 497c3bd1bd884f4f2c60870a096b19c1a8ceb9fd

[Jian Yu]

Hi Andreas,

As per your suggestions, fetching default layout for a directory will be done in lfs_getstripe()->...->cb_getstripe(). If get_lmd_info() returns -ENODATA for a directory that does not have trusted.lov xattr, cb_getstripe() should get the lov_user_md data from ROOT FID, and then print the layout information in llapi_lov_dump_user_lmm().

One solution would be to special-case the [FID_SEQ_ROOT, FID_OID_ROOT, 0] lookup in the directory in ioctl(IOC_MDC_GETFILESTRIPE) to convert this ioctl onto the actual ROOT FID, since this is out of the critical code path, and is unlikely to cause any problems for existing files. It should treat -ENOENT as -ENODATA, in case it is running on an old client that does not have this feature, and it will just keep the same behaviour as today.

That will probably involve taking the core of ll_lov_getstripe_ea_info() into a separate helper function that allows passing the ROOT FID, while the original ll_lov_getstripe_ea_info() gets the FID from inode.

One upcoming issue with explicitly using the ROOT FID is that this will complicate things is the patch https://review.whamcloud.com/28972 "LU-9982 lustre: Clients striping from mapped FID in nodemap", since that feature will allow clients to inherit layouts from a non-ROOT directory based on their nodemap. In that case, it might make sense to handle the ROOT FID getstripe to be mapped to the nodemap root layout (if set) so that the "lfs getstripe" output is consistent.

[Andreas Dilger]

Jian, is the default layout for the directory going to be fetched from the ROOT FID inside the kernel or from the "lfs getstripe" command? Fetching it from the kernel simplifies some issues for userspace applications, but has the drawback that tools like "tar" will make a copy of the default trusted.lov xattr for every directory in the filesystem which doesn't have its own xattr.

Doing it in "lfs getstripe" avoids this issue, but may have other issues (e.g. opening $MOUNT/.lustre/fid is only accessible to root, and is not available in subdirectory mounts.

[Jian Yu]

According to Andreas' comments, I'm working on the patch to fetch the layout from the ROOT FID [FID_SEQ_ROOT, FID_OID_ROOT, 0].

[Jian Yu]

Hi Nathan,
Let me look into this and work on it.

[Nathan Dauchy (Inactive)]

Jian.

I just wanted to make sure you were aware that this is still a problem, even with LU-10629 fixed or deleting the stripe info on a directory so that it should implicitly inherit the filesystem default.  I agree with the statement that Andreas made "We need some way to fetch the actual default layout that will be used when new files will be created in that directory."

Thanks,
Nathan