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X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 2SS4jI4ZFNMkNZ2PqOo7Gf5xFo1n4c4bZuz0j2dFsAbmcabHpJG9NVUUsoXNSKMCaggT4MyzbWkwxRf/G4RBtg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR10MB7836 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-04-04_10,2024-04-04_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 adultscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2404010000 definitions=main-2404040096 X-Proofpoint-GUID: 1ilJB9Gujjtkc9jpkdTer1dmGVg6LqEp X-Proofpoint-ORIG-GUID: 1ilJB9Gujjtkc9jpkdTer1dmGVg6LqEp >>> - if (available < (int)args->maxlen && !(flags & XFS_ALLOC_FLAG_CHECK)) { >>> - args->maxlen = available; >>> + alloc_len = args->maxlen + (args->alignment - 1) + args->minalignslop; >> >> I added some kernel logs to assist debugging, and if I am reading them >> correctly, for ext #2 allocation we had at this point: >> >> longest = 46, alloc_len = 47, args->minlen=30, maxlen=32, alignslop=0 >> available=392; longest < alloc_len, so we set args->maxlen = args->minlen (= >> 30) > > Why was args->minlen set to 30? Where did that value come from? i.e. > That is not correctly sized/aligned for force alignment - it should > be rounded down to 16 fsbs, right? I could not recreate this exact scenario, but another similar one occurred which gave: /root/mnt2/file_2425: EXT: FILE-OFFSET BLOCK-RANGE AG AG-OFFSET TOTAL 0: [0..431]: 489600..490031 2 (131200..131631) 432 1: [432..511]: 529408..529487 2 (171008..171087) 80 # For allocating EXT #0, in xfs_bmap_select_minlen() we had initially args->minlen=0, maxlen=64 blen=70 then blen -= alignment (=16), an finally condition blen < args->maxlen passed and have minlen = 54 Then in xfs_alloc_space_available(), for check (longest < alloc_len) near the end, at that point we have: longest=70, alloc_len=79, args->minlen=54, maxlen=64, alignslop=0 available=155, and so we set maxlen = minlen = 54 Then in xfs_alloc_fix_len(), initially args->mod=0, prod=16, minlen=54, maxlen=54, len=54 rlen=54 And we end up with the 54 FSB extent. > > I'm guessing that "30" is (longest - alignment) = 46 - 16 = 30? And > then it wasn't rounded down from there? > >> For ext3: >> longest = 32, alloc_len = 17, args->minlen=2, args->maxlen=2, alignslop=0, >> available=362; longest > alloc_len, so do nothing > > Same issue here - for a forced align allocation, minlen needs to be > bound to alignment constraints. If minlen is set like this, then the > allocation will always return a 2 block extent if they exist. > > IOWs, the allocation constraints are not correctly aligned, but the > allocation is doing exactly what the constraints say it is allowed > to do. Therefore the issue is in the constraint setup (args->minlen) > for forced alignment and not the allocation code that selects a > an args->minlen extent that is not correctly sized near ENOSPC. > > I'm guessing that we need something like the (untested) patch below > to ensure args->minlen is properly aligned.... > > -Dave. For some reason that diff got excluded or mangled when I tried to reply. Anyway, it seems to work ok, but that's based only on a quite limited amount of testing. Thanks, John