Details
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Bug
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Resolution: Fixed
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Major
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Lustre 2.4.0, Lustre 2.4.1
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None
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Lustre 2.4.1 RHEL6 2.6.32-358.18.1.el6_lustre.x86_64
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4
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11777
Description
"lfs_migrate -y" aborts with this error
cannot swap layouts between <filename> and a volatile file (Operation not permitted)
This seems to happen for all files. The lfs_migrate operation aborts on the first file.
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Issue Links
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But finally may be it is related to LU-3834, after my recent discovery there that the layouts swap-back upon failure may not work as expected!
Andreas, LU-3834 is about how to handle/recover-from any layout swap failures during HSM Restore ops and avoid leaving file in inconsistent state, this ticket is for a specific condition and consequence. I will try to push a patch soon based on your already+very detailled analysis, thanks !!
Bruno, does the layout swap failure here have any relation to LU-3834? I saw many leaked objects after failures calling "lfs migrate" on an IGIF file.
I also see that the failure in "lfs migrate" is causing volatile inodes to be leaked on the MDT. I see:
e2fsck 1.42.7.wc1 (12-Apr-2013) Pass 1: Checking inodes, blocks, and sizes Pass 2: Checking directory structure Pass 3: Checking directory connectivity Pass 4: Checking reference counts Unattached inode 116 Connect to /lost+found? no Unattached inode 117 Connect to /lost+found? no Unattached inode 118 Connect to /lost+found? no Unattached inode 409 Connect to /lost+found? no
The unattached inodes look like:
debugfs 1.42.7.wc2 (12-Apr-2013) debugfs: stat <116> Inode: 116 Type: regular Mode: 0644 Flags: 0x0 Generation: 2124528570 Version: 0x00000001:00001b6d User: 0 Group: 0 Size: 0 File ACL: 0 Directory ACL: 0 Links: 1 Blockcount: 0 Fragment: Address: 0 Number: 0 Size: 0 ctime: 0x5296625c:00000000 -- Wed Nov 27 14:21:32 2013 atime: 0x52966270:00000000 -- Wed Nov 27 14:21:52 2013 mtime: 0x52966270:00000000 -- Wed Nov 27 14:21:52 2013 crtime: 0x5296625c:087ac7fc -- Wed Nov 27 14:21:32 2013 Size of extra inode fields: 28 Extended attributes stored in inode body: lma = "00 00 00 00 00 00 00 00 00 04 00 00 02 00 00 00 45 07 00 00 00 00 00 00 " (24) lma: fid=[0x200000400:0x745:0x0] compat=0 incompat=0 link = "df f1 ea 11 01 00 00 00 3a 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 22 00 00 00 02 00 00 00 07 00 00 00 01 00 00 00 00 2e 0c 13 14 12 3a 56 4f 4c 41 54 49 4c 45 3a 3a " (58) lov = "d0 0b d1 0b 01 00 00 00 45 07 00 00 00 00 00 00 00 04 00 00 02 00 00 00 00 00 10 00 01 00 01 00 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 02 00 00 00 " (56) BLOCKS:
where the "link" xattr is the "^.L^S^T^R:VOLATILE" string.
I investigated this on my home system, since I was seeing this problem intermittently as well.
It looks like the problem is caused in my case because the problematic files were created with Lustre 1.8 or earlier and have IGIF FIDs (these show as inode number < 4B, ). Migrating files created under 2.x is OK (these have very large inode numbers):
$ ls -i /mnt/tmp/tmp/1M 144115440203858997 1024 /mnt/tmp/tmp/1M $ lfs path2fid /mnt/tmp/tmp/1M [0x200003ab4:0x435:0x0] $ lfs migrate -i 1 /mnt/tmp/tmp/1M $ ls -i /mnt/tmp/tmp/4M 2422700 4096 /mnt/tmp/tmp/4M $ lfs path2fid /mnt/tmp/tmp/4M [0x24f7ac:0x2d77b0e5:0x0] $ lfs migrate -i 1 /mnt/tmp/tmp/4M cannot swap layouts between /mnt/tmp/tmp/4M and a volatile file (Operation not permitted) error: migrate: migrate stripe file '/mnt/tmp/tmp/4M' failed
This is because there is a check in mdd_swap_layouts_allowed() that prevents layout swap for IGIF FIDs:
static int mdd_layout_swap_allowed(const struct lu_env *env, struct mdd_object *o1, struct mdd_object *o2) { const struct lu_fid *fid1, *fid2; fid1 = mdo2fid(o1); fid2 = mdo2fid(o2); if (!fid_is_norm(fid1) || !fid_is_norm(fid2) || (mdd_object_type(o1) != mdd_object_type(o2))) RETURN(-EPERM);
This was done to prevent clients from being able to swap the contents of regular files with internal system files by using their (internal) IGIF FIDs.
I'm not yet sure how to detect the difference between filenames that are visible in the namespace and ones that are accessed by IGIF FID. It does seem that "lfs fid2path" and $MOUNT/.lustre/fid/ can detect the difference between IGIF and FID access with my 2.4.1 server. I took a normal FID and then figured out its IGIF FID by looking at the MDT inode's inum/generation directly, and got a "no such file or directory", so that is a good start.
However, it also appears that some files in the MDT root directory (e.g. backups of fld, seq_srv, seq_cli, etc) are readable via $MOUNT/.lustre/fid/ and have an IGIF FID assigned to them. The shell also thinks that these FIDs have write permission (i.e. test -w "$MOUNT/.lustre/fid/[0x2686:0xc40fa169:0x0]" returns 0), even though I get a permission denied error trying to modify them, so normal write permission checks will fail. That might be a problem with LFSCK adding these files into the OI when they shouldn't be. The originals of these files correctly have SEQ 0x200000001 and get an error from obf_lookup(), but I think it makes sense to mark all files in the top-level MDT/OST root directory inaccessible, and only add files under ROOT to the OI.
In the short term, "lfs_migrate" should fall back to using rsync internally if "lfs migrate" returns an error, but I haven't tested this. It would also be useful to fix the error message printed by "lfs migrate", since I find the current one confusing. I don't think it needs to mention anything about volatile files.
Andreas,
After the failure, is the original file still accessible ?
Also, since it appears the main problem for this ticket is that trying "lfs migrate" on 1.8 files with IGIF fids will fail and leak volatile objects on MDT, why not 1st change test in mdd_layout_swap_allowed() by adding/allowing also fid_is_igif() files ? Then we will address the special cases of system/ROOT files and the failure/recovery.
Or do you still think all cases must be handled in "lfs migrate" by switching to rsync if not a system/ROOT file, and the leak to be addressed separately ?