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2021-09-17xfs: repair refcount btreesrepair-ag-btrees_2021-09-17Darrick J. Wong
Reconstruct the refcount data from the rmap btree. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-09-17xfs: repair inode btreesDarrick J. Wong
Use the rmapbt to find inode chunks, query the chunks to compute hole and free masks, and with that information rebuild the inobt and finobt. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-09-17xfs: repair free space btreesDarrick J. Wong
Rebuild the free space btrees from the gaps in the rmap btree. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-09-17xfs: always rescan allegedly healthy per-ag metadata after repairDarrick J. Wong
After an online repair function runs for a per-AG metadata structure, sc->sick_mask is supposed to reflect the per-AG metadata that the repair function fixed. Our next move is to re-check the metadata to assess the completeness of our repair, so we don't want the rebuilt structure to be excluded from the rescan just because the health system previously logged a problem with the data structure. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-09-17xfs: implement online scrubbing of rtsummary infoscrub-rtsummary_2021-09-17Darrick J. Wong
Finish the realtime summary scrubber by adding the functions we need to compute a fresh copy of the rtsummary info and comparing it to the copy on disk. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-09-17xfs: move the realtime summary file scrubber to a separate source fileDarrick J. Wong
Move the realtime summary file checking code to a separate file in preparation to actually implement it. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-09-17xfs: get our own reference to inodes that we want to scrubDarrick J. Wong
When we want to scrub a file, get our own reference to the inode unconditionally. This will make disposal rules simpler in the long run. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-09-17xfs: create a big array data structureDarrick J. Wong
Create a simple 'big array' data structure for storage of fixed-size metadata records that will be used to reconstruct a btree index. For repair operations, the most important operations are append, iterate, and sort. Earlier implementations of the big array used linked lists and suffered from severe problems -- pinning all records in kernel memory was not a good idea and frequently lead to OOM situations; random access was very inefficient; and record overhead for the lists was unacceptably high at 40-60%. Therefore, the big memory array relies on the 'xfile' abstraction, which creates a memfd file and stores the records in page cache pages. Since the memfd is created in tmpfs, the memory pages can be pushed out to disk if necessary and we have a built-in usage limit of 50% of physical memory. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-09-17xfs: log EFIs for all btree blocks being used to stage a btreerepair-prep-for-bulk-loading_2021-09-17Darrick J. Wong
We need to log EFIs for every extent that we allocate for the purpose of staging a new btree so that if we fail then the blocks will be freed during log recovery. Add a function to relog the EFIs, so that repair can relog them all every time it creates a new btree block, which will help us to avoid pinning the log tail. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-09-17xfs: add debug knobs to control btree bulk load slack factorsDarrick J. Wong
Add some debug knobs so that we can control the leaf and node block slack when rebuilding btrees. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-09-17xfs: implement block reservation accounting for btrees we're stagingDarrick J. Wong
Create a new xrep_newbt structure to encapsulate a fake root for creating a staged btree cursor as well as to track all the blocks that we need to reserve in order to build that btree. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-09-17xfs: convert xbitmap to interval treerepair-bitmap-rework_2021-09-17Darrick J. Wong
Convert the xbitmap code to use interval trees instead of linked lists. This reduces the amount of coding required to handle the disunion operation and in the future will make it easier to set bits in arbitrary order yet later be able to extract maximally sized extents, which we'll need for rebuilding certain structures. We define our own interval tree type so that it can deal with 64-bit indices even on 32-bit machines. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-09-17xfs: reap large extents when possibleDarrick J. Wong
When we're freeing extents that have been set in a bitmap, break the bitmap extent into multiple sub-extents organized by fate, and reap the extents. This enables us to dispose of old resources more efficiently than doing them block by block. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-09-17xfs: drop the _safe behavior from the xbitmap foreach macroDarrick J. Wong
It's not safe to edit bitmap intervals while we're iterating them with for_each_xbitmap_extent. None of the existing callers actually need that ability anyway, so drop the safe variable. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-09-17xfs: remove the for_each_xbitmap_ helpersDarrick J. Wong
Remove the for_each_xbitmap_ macros in favor of proper iterator functions. We'll soon be switching this data structure over to an interval tree implementation, which means that we can't allow callers to modify the bitmap during iteration without telling us. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-09-17xfs: use deferred frees to reap old btree blocksrepair-reap-fixes_2021-09-17Darrick J. Wong
Use deferred frees (EFIs) to reap the blocks of a btree that we just replaced. This helps us to shrink the window in which those old blocks could be lost due to a system crash, though we try to flush the EFIs every few hundred blocks so that we don't also overflow the transaction reservations during and after we commit the new btree. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-09-17xfs: only allow reaping of per-AG blocks in xrep_reap_extentsDarrick J. Wong
Now that we've refactored btree cursors to require the caller to pass in a perag structure, there are numerous problems in xrep_reap_extents if it's being called to reap extents for an inode metadata repair. We don't have any repair functions that can do that, so drop the support for now. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-09-17xfs: only invalidate blocks if we're going to free themDarrick J. Wong
When we're discarding old btree blocks after a repair, only invalidate the buffers for the ones that we're freeing -- if the metadata was crosslinked with another data structure, we don't want to touch it. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-09-17xfs: simplify xfs_rmap_lookup_le call sitesDarrick J. Wong
Most callers of xfs_rmap_lookup_le will retrieve the btree record immediately if the lookup succeeds. The overlapped version of this function (xfs_rmap_lookup_le_range) will return the record if the lookup succeeds, so make the regular version do it too. Get rid of the useless len argument, since it's not part of the lookup key. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-09-17xfs: check the reference counts of gaps in the refcount btreescrub-fix-checking-gaps_2021-09-17Darrick J. Wong
Gaps in the reference count btree are also significant -- for these regions, there must not be any overlapping reverse mappings. We don't currently check this, so make the refcount scrubber more complete. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-09-17xfs: check quota files for unwritten extentsDarrick J. Wong
Teach scrub to flag quota files containing unwritten extents. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-09-17xfs: teach scrub to check for adjacent bmaps when rmap larger than bmapDarrick J. Wong
When scrub is checking file fork mappings against rmap records and the rmap record starts before or ends after the bmap record, check the adjacent bmap records to make sure that they're adjacent to the one we're checking. This helps us to detect cases where the rmaps cover territory that the bmaps do not. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-09-17xfs: online checking of the free rt extent countDarrick J. Wong
Teach the summary count checker to count the number of free realtime extents and compare that to the superblock copy. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-09-17xfs: check btree keys reflect the child blockDarrick J. Wong
When scrub is checking a non-root btree block, it should make sure that the keys in the parent btree block accurately capture the keyspace that the child block stores. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-08-20xfs: fix perag structure refcounting error when scrub failsxfs-5.15-merge-5Darrick J. Wong
The kernel test robot found the following bug when running xfs/355 to scrub a bmap btree: XFS: Assertion failed: !sa->pag, file: fs/xfs/scrub/common.c, line: 412 ------------[ cut here ]------------ kernel BUG at fs/xfs/xfs_message.c:110! invalid opcode: 0000 [#1] SMP PTI CPU: 2 PID: 1415 Comm: xfs_scrub Not tainted 5.14.0-rc4-00021-g48c6615cc557 #1 Hardware name: Hewlett-Packard p6-1451cx/2ADA, BIOS 8.15 02/05/2013 RIP: 0010:assfail+0x23/0x28 [xfs] RSP: 0018:ffffc9000aacb890 EFLAGS: 00010202 RAX: 0000000000000000 RBX: ffffc9000aacbcc8 RCX: 0000000000000000 RDX: 00000000ffffffc0 RSI: 000000000000000a RDI: ffffffffc09e7dcd RBP: ffffc9000aacbc80 R08: ffff8881fdf17d50 R09: 0000000000000000 R10: 000000000000000a R11: f000000000000000 R12: 0000000000000000 R13: ffff88820c7ed000 R14: 0000000000000001 R15: ffffc9000aacb980 FS: 00007f185b955700(0000) GS:ffff8881fdf00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f7f6ef43000 CR3: 000000020de38002 CR4: 00000000001706e0 Call Trace: xchk_ag_read_headers+0xda/0x100 [xfs] xchk_ag_init+0x15/0x40 [xfs] xchk_btree_check_block_owner+0x76/0x180 [xfs] xchk_btree_get_block+0xd0/0x140 [xfs] xchk_btree+0x32e/0x440 [xfs] xchk_bmap_btree+0xd4/0x140 [xfs] xchk_bmap+0x1eb/0x3c0 [xfs] xfs_scrub_metadata+0x227/0x4c0 [xfs] xfs_ioc_scrub_metadata+0x50/0xc0 [xfs] xfs_file_ioctl+0x90c/0xc40 [xfs] __x64_sys_ioctl+0x83/0xc0 do_syscall_64+0x3b/0xc0 The unusual handling of errors while initializing struct xchk_ag is the root cause here. Since the beginning of xfs_scrub, the goal of xchk_ag_read_headers has been to read all three AG header buffers and attach them both to the xchk_ag structure and the scrub transaction. Corruption errors on any of the three headers doesn't necessarily trigger an immediate return to userspace, because xfs_scrub can also tell us to /fix/ the problem. In other words, it's possible for the xchk_ag init functions to return an error code and a partially filled out structure so that scrub can use however much information it managed to pull. Before 5.15, it was sufficient to cancel (or commit) the scrub transaction on the way out of the scrub code to release the buffers. Ccommit 48c6615cc557 added a reference to the perag structure to struct xchk_ag. Since perag structures are not attached to transactions like buffers are, this adds the requirement that the perag ref be released explicitly. The scrub teardown function xchk_teardown was amended to do this for the xchk_ag embedded in struct xfs_scrub. Unfortunately, I forgot that certain parts of the scrub code probe multiple AGs and therefore handle the initialization and cleanup on their own. Specifically, the bmbt scrubber will initialize it long enough to cross-reference AG metadata for btree blocks and for the extent mappings in the bmbt. If one of the AG headers is corrupt, the init function returns with a live perag structure reference and some of the AG header buffers. If an error occurs, the cross referencing will be noted as XCORRUPTion and skipped, but the main scrub process will move on to the next record. It is now necessary to release the perag reference before we try to analyze something from a different AG, or else we'll trip over the assertion noted above. Fixes: 48c6615cc557 ("xfs: grab active perag ref when reading AG headers") Reported-by: kernel test robot <oliver.sang@intel.com> Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
2021-08-19xfs: convert bp->b_bn references to xfs_buf_daddr()Dave Chinner
Stop directly referencing b_bn in code outside the buffer cache, as b_bn is supposed to be used only as an internal cache index. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-08-19xfs: introduce xfs_buf_daddr()Dave Chinner
Introduce a helper function xfs_buf_daddr() to extract the disk address of the buffer from the struct xfs_buf. This will replace direct accesses to bp->b_bn and bp->b_maps[0].bm_bn, as well as the XFS_BUF_ADDR() macro. This patch introduces the helper function and replaces all uses of XFS_BUF_ADDR() as this is just a simple sed replacement. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-08-19xfs: introduce xfs_sb_is_v5 helperDave Chinner
Rather than open coding XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5 checks everywhere, add a simple wrapper to encapsulate this and make the code easier to read. This allows us to remove the xfs_sb_version_has_v3inode() wrapper which is only used in xfs_format.h now and is just a version number check. There are a couple of places where we should be checking the mount feature bits rather than the superblock version (e.g. remount), so those are converted to use xfs_has_crc(mp) instead. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-08-19xfs: convert xfs_sb_version_has checks to use mount featuresDave Chinner
This is a conversion of the remaining xfs_sb_version_has..(sbp) checks to use xfs_has_..(mp) feature checks. This was largely done with a vim replacement macro that did: :0,$s/xfs_sb_version_has\(.*\)&\(.*\)->m_sb/xfs_has_\1\2/g<CR> A couple of other variants were also used, and the rest touched up by hand. $ size -t fs/xfs/built-in.a text data bss dec hex filename before 1127533 311352 484 1439369 15f689 (TOTALS) after 1125360 311352 484 1437196 15ee0c (TOTALS) Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-08-19xfs: convert scrub to use mount-based feature checksDave Chinner
The scrub feature checks are the last place that the superblock feature checks are used. Convert them to mount based feature checks. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-08-19xfs: replace XFS_FORCED_SHUTDOWN with xfs_is_shutdownDave Chinner
Remove the shouty macro and instead use the inline function that matches other state/feature check wrapper naming. This conversion was done with sed. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-08-19xfs: convert remaining mount flags to state flagsDave Chinner
The remaining mount flags kept in m_flags are actually runtime state flags. These change dynamically, so they really should be updated atomically so we don't potentially lose an update due to racing modifications. Convert these remaining flags to be stored in m_opstate and use atomic bitops to set and clear the flags. This also adds a couple of simple wrappers for common state checks - read only and shutdown. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-08-19xfs: convert mount flags to featuresDave Chinner
Replace m_flags feature checks with xfs_has_<feature>() calls and rework the setup code to set flags in m_features. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-08-19xfs: replace xfs_sb_version checks with feature flag checksDave Chinner
Convert the xfs_sb_version_hasfoo() to checks against mp->m_features. Checks of the superblock itself during disk operations (e.g. in the read/write verifiers and the to/from disk formatters) are not converted - they operate purely on the superblock state. Everything else should use the mount features. Large parts of this conversion were done with sed with commands like this: for f in `git grep -l xfs_sb_version_has fs/xfs/*.c`; do sed -i -e 's/xfs_sb_version_has\(.*\)(&\(.*\)->m_sb)/xfs_has_\1(\2)/' $f done With manual cleanups for things like "xfs_has_extflgbit" and other little inconsistencies in naming. The result is ia lot less typing to check features and an XFS binary size reduced by a bit over 3kB: $ size -t fs/xfs/built-in.a text data bss dec hex filenam before 1130866 311352 484 1442702 16038e (TOTALS) after 1127727 311352 484 1439563 15f74b (TOTALS) Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-08-19xfs: start documenting common units and tags used in tracepointsDarrick J. Wong
Because there are a lot of tracepoints that express numeric data with an associated unit and tag, document what they are to help everyone else keep these thigns straight. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
2021-08-19xfs: decode scrub flags in ftrace outputDarrick J. Wong
When using pretty-printed scrub tracepoints, decode the meaning of the scrub flags as strings for easier reading. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
2021-08-19xfs: standardize inode generation formatting in ftrace outputDarrick J. Wong
Always print inode generation in hexadecimal and preceded with the unit "gen". Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
2021-08-19xfs: resolve fork names in trace outputDarrick J. Wong
Emit whichfork values as text strings in the ftrace output. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
2021-08-19xfs: disambiguate units for ftrace fields tagged "len"Darrick J. Wong
Some of our tracepoints have a field known as "len". That name doesn't describe any units, which makes the fields not very useful. Rename the fields to capture units and ensure the format is hexadecimal. "fsbcount" are in units of fs blocks "bbcount" are in units of 512b blocks "ireccount" are in units of inodes Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
2021-08-19xfs: disambiguate units for ftrace fields tagged "offset"Darrick J. Wong
Some of our tracepoints describe fields as "offset". That name doesn't describe any units, which makes the fields not very useful. Rename the fields to capture units and ensure the format is hexadecimal. "fileoff" means file offset, in units of fs blocks "pos" means file offset, in bytes "forkoff" means inode fork offset, in bytes The one remaining "offset" value is for iclogs, since that's the byte offset of the end of where we've written into the current iclog. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
2021-08-19xfs: standardize rmap owner number formatting in ftrace outputDarrick J. Wong
Always print rmap owner number in hexadecimal and preceded with the unit "owner". Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
2021-08-19xfs: standardize AG block number formatting in ftrace outputDarrick J. Wong
Always print allocation group block numbers in hexadecimal and preceded with the unit "agbno". Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
2021-08-19xfs: standardize AG number formatting in ftrace outputDarrick J. Wong
Always print allocation group numbers in hexadecimal and preceded with the unit "agno". Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
2021-08-19xfs: standardize inode number formatting in ftrace outputDarrick J. Wong
Always print inode numbers in hexadecimal and preceded with the unit "ino" or "agino", as apropriate. Fix one tracepoint that used "ino %u" for an inode btree block count to reduce confusion. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
2021-08-19xfs: fix incorrect unit conversion in scrub tracepointDarrick J. Wong
XFS_DADDR_TO_FSB converts a raw disk address (in units of 512b blocks) to a raw disk address (in units of fs blocks). Unfortunately, the xchk_block_error_class tracepoints incorrectly uses this to decode xfs_daddr_t into segmented AG number and AG block addresses. Use the correct translation code. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
2021-08-18xfs: mark the record passed into xchk_btree functions as constDarrick J. Wong
xchk_btree calls a user-supplied function to validate each btree record that it finds. Those functions are not supposed to change the record data, so mark the parameter const. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2021-08-18xfs: make the record pointer passed to query_range functions constDarrick J. Wong
The query_range functions are supposed to call a caller-supplied function on each record found in the dataset. These functions don't own the memory storing the record, so don't let them change the record. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2021-08-18xfs: remove unnecessary agno variable from struct xchk_agDarrick J. Wong
Now that we always grab an active reference to a perag structure when dealing with perag metadata, we can remove this unnecessary variable. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2021-08-09xfs: replace kmem_alloc_large() with kvmalloc()Dave Chinner
There is no reason for this wrapper existing anymore. All the places that use KM_NOFS allocation are within transaction contexts and hence covered by memalloc_nofs_save/restore contexts. Hence we don't need any special handling of vmalloc for large IOs anymore and so special casing this code isn't necessary. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-08-09xfs: grab active perag ref when reading AG headersDarrick J. Wong
This patch prepares scrub to deal with the possibility of tearing down entire AGs by changing the order of resource acquisition to match the rest of the XFS codebase. In other words, scrub now grabs AG resources in order of: perag structure, then AGI/AGF/AGFL buffers, then btree cursors; and releases them in reverse order. This requires us to distinguish xchk_ag_init callers -- some are responding to a user request to check AG metadata, in which case we can return ENOENT to userspace; but other callers have an ondisk reference to an AG that they're trying to cross-reference. In this second case, the lack of an AG means there's ondisk corruption, since ondisk metadata cannot point into nonexistent space. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>