When following a trailing symlink in rcu-walk mode it's possible to
succeed in getting the ->get_link() method pointer but the link path
string be deallocated while it's being used.

Utilize the rcu mechanism to mitigate this risk.

Suggested-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Ian Kent <raven@themaw.net>

When following a trailing symlink in rcu-walk mode it's possible for
the dentry to become invalid between the last dentry seq lock check
and getting the link (eg. an unlink) leading to a backtrace similar
to this:

crash> bt
PID: 10964  TASK: ffff951c8aa92f80  CPU: 3   COMMAND: "TaniumCX"
…
 torvalds#7 [ffffae44d0a6fbe0] page_fault at ffffffff8d6010fe
    [exception RIP: unknown or invalid address]
    RIP: 0000000000000000  RSP: ffffae44d0a6fc90  RFLAGS: 00010246
    RAX: ffffffff8da3cc80  RBX: ffffae44d0a6fd30  RCX: 0000000000000000
    RDX: ffffae44d0a6fd98  RSI: ffff951aa9af3008  RDI: 0000000000000000
    RBP: 0000000000000000   R8: ffffae44d0a6fb94   R9: 0000000000000000
    R10: ffff951c95d8c318  R11: 0000000000080000  R12: ffffae44d0a6fd98
    R13: ffff951aa9af3008  R14: ffff951c8c9eb840  R15: 0000000000000000
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 torvalds#8 [ffffae44d0a6fc90] trailing_symlink at ffffffff8cf24e61
 torvalds#9 [ffffae44d0a6fcc8] path_lookupat at ffffffff8cf261d1
torvalds#10 [ffffae44d0a6fd28] filename_lookup at ffffffff8cf2a700
torvalds#11 [ffffae44d0a6fe40] vfs_statx at ffffffff8cf1dbc4
torvalds#12 [ffffae44d0a6fe98] __do_sys_newstat at ffffffff8cf1e1f9
torvalds#13 [ffffae44d0a6ff38] do_syscall_64 at ffffffff8cc0420b

Most of the time this is not a problem because the inode is unchanged
while the rcu read lock is held.

But xfs can re-use inodes which can result in the inode ->get_link()
method becoming invalid (or NULL).

This case needs to be checked for in fs/namei.c:get_link() and if
detected the walk re-started.

Signed-off-by: Ian Kent <raven@themaw.net>

Use swap() in order to make code cleaner. Issue found by coccinelle.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Changcheng Deng <deng.changcheng@zte.com.cn>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Fix following checkincludes.pl warning:
./fs/xfs/xfs_super.c: xfs_btree.h is included more than once.

The include is in line 15. Remove the duplicated here.

Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

If writeback I/O to a COW extent fails, the COW fork blocks are
punched out and the data fork blocks left alone. It is possible for
COW fork blocks to overlap non-shared data fork blocks (due to
cowextsz hint prealloc), however, and writeback unconditionally maps
to the COW fork whenever blocks exist at the corresponding offset of
the page undergoing writeback. This means it's quite possible for a
COW fork extent to overlap delalloc data fork blocks, writeback to
convert and map to the COW fork blocks, writeback to fail, and
finally for ioend completion to cancel the COW fork blocks and leave
stale data fork delalloc blocks around in the inode. The blocks are
effectively stale because writeback failure also discards dirty page
state.

If this occurs, it is likely to trigger assert failures, free space
accounting corruption and failures in unrelated file operations. For
example, a subsequent reflink attempt of the affected file to a new
target file will trip over the stale delalloc in the source file and
fail. Several of these issues are occasionally reproduced by
generic/648, but are reproducible on demand with the right sequence
of operations and timely I/O error injection.

To fix this problem, update the ioend failure path to also punch out
underlying data fork delalloc blocks on I/O error. This is analogous
to the writeback submission failure path in xfs_discard_page() where
we might fail to map data fork delalloc blocks and consistent with
the successful COW writeback completion path, which is responsible
for unmapping from the data fork and remapping in COW fork blocks.

Fixes: 787eb48 ("xfs: fix and streamline error handling in xfs_end_io")
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

The owner info parameter is always NULL, so get rid of the parameter.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Chandan Babu R <chandan.babu@oracle.com>

We only use EFIs to free metadata blocks -- not regular data/attr fork
extents.  Remove all the fields that we never use, for a net reduction
of 16 bytes.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Chandan Babu R <chandan.babu@oracle.com>

xfs_bmap_add_free isn't a block mapping function; it schedules deferred
freeing operations for a later point in a compound transaction chain.
While it's primarily used by bunmapi, its use has expanded beyond that.
Move it to xfs_alloc.c and rename the function since it's now general
freeing functionality.  Bring the slab cache bits in line with the
way we handle the other intent items.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Chandan Babu R <chandan.babu@oracle.com>

Create slab caches for the high-level structures that coordinate
deferred intent items, since they're used fairly heavily.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Chandan Babu R <chandan.babu@oracle.com>

Rearrange these structs to reduce the amount of unused padding bytes.
This saves eight bytes for each of the three structs changed here, which
means they're now all (rmap/bmap are 64 bytes, refc is 32 bytes) even
powers of two.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Chandan Babu R <chandan.babu@oracle.com>

Now that we've gotten rid of the kmem_zone_t typedef, rename the
variables to _cache since that's what they are.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Chandan Babu R <chandan.babu@oracle.com>

Remove these typedefs by referencing kmem_cache directly.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Chandan Babu R <chandan.babu@oracle.com>

Now that we have the infrastructure to track the max possible height of
each btree type, we can create a separate slab cache for cursors of each
type of btree.  For smaller indices like the free space btrees, this
means that we can pack more cursors into a slab page, improving slab
utilization.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

Add code for all five btree types so that we can compute the absolute
maximum possible btree height for each btree type.  This is a setup for
the next patch, which makes every btree type have its own cursor cache.

The functions are exported so that we can have xfs_db report the
absolute maximum btree heights for each btree type, rather than making
everyone run their own ad-hoc computations.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

Nobody uses this symbol anymore, so kill it.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Chandan Babu R <chandan.babu@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

Instead of assuming that the hardcoded XFS_BTREE_MAXLEVELS value is big
enough to handle the maximally tall rmap btree when all blocks are in
use and maximally shared, let's compute the maximum height assuming the
rmapbt consumes as many blocks as possible.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Chandan Babu R <chandan.babu@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

During review of the next patch, Dave remarked that he found these two
btree geometry calculation functions lacking in documentation and that
they performed more work than was really necessary.

These functions take the same parameters and have nearly the same logic;
the only real difference is in the return values.  Reword the function
comment to make it clearer what each function does, and move them to be
adjacent to reinforce their relation.

Clean up both of them to stop opencoding the howmany functions, stop
using the uint typedefs, and make them both support computations for
more than 2^32 leaf records, since we're going to need all of the above
for files with large data forks and large rmap btrees.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

…tion

Compute the actual maximum AG btree height for deciding if a per-AG
block reservation is critically low.  This only affects the sanity check
condition, since we /generally/ will trigger on the 10% threshold.  This
is a long-winded way of saying that we're removing one more usage of
XFS_BTREE_MAXLEVELS.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

Years ago when XFS was thought to be much more simple, we introduced
m_ag_maxlevels to specify the maximum btree height of per-AG btrees for
a given filesystem mount.  Then we observed that inode btrees don't
actually have the same height and split that off; and now we have rmap
and refcount btrees with much different geometries and separate
maxlevels variables.

The 'ag' part of the name doesn't make much sense anymore, so rename
this to m_alloc_maxlevels to reinforce that this is the maximum height
of the *free space* btrees.  This sets us up for the next patch, which
will add a variable to track the maximum height of all AG btrees.

(Also take the opportunity to improve adjacent comments and fix minor
style problems.)

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

To support future btree code, we need to be able to size btree cursors
dynamically for very large btrees.  Switch the maxlevels computation to
use the precomputed values in the superblock, and create cursors that
can handle a certain height.  For now, we retain the btree cursor cache
that can handle up to 9-level btrees, though a subsequent patch
introduces separate caches for each btree type, where each cache's
objects will be exactly tall enough to handle the specific btree type.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

Encode the maximum btree height in the cursor, since we're soon going to
allow smaller cursors for AG btrees and larger cursors for file btrees.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

Refactor btree allocation to a common helper.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Chandan Babu R <chandan.babu@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

Reduce the size of the btree cursor structure some more by rearranging
fields to eliminate unused space.  While we're at it, fix the ragged
indentation and a spelling error.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

Split out the btree level information into a separate struct and put it
at the end of the cursor structure as a VLA.  Files with huge data forks
(and in the future, the realtime rmap btree) will require the ability to
support many more levels than a per-AG btree cursor, which means that
we're going to create per-btree type cursor caches to conserve memory
for the more common case.

Note that a subsequent patch actually introduces dynamic cursor heights.
This one merely rearranges the structure to prepare for that.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Chandan Babu R <chandan.babu@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

Reorganize struct xchk_btree so that we can dynamically size the context
structure to fit the type of btree cursor that we have.  This will
enable us to use memory more efficiently once we start adding very tall
btree types.  Right-size the lastkey array to match the number of *node*
levels in the tree so that we stop wasting space.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

The btree scrubbing code checks that the records (or keys) that it finds
in a btree block are all in order by calling the btree cursor's
->recs_inorder function.  This of course makes no sense for the first
item in the block, so we switch that off with a separate variable in
struct xchk_btree.

Christoph helped me figure out that the variable is unnecessary, since
we just accessed bc_ptrs[level] and can compare that against zero.  Use
that, and save ourselves some memory space.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

We're never going to run more than 4 billion btree operations on a
refcount cursor, so shrink the field to an unsigned int to reduce the
structure size.  Fix whitespace alignment too.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

This field isn't used by anyone, so get rid of it.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

During review of subsequent patches, Dave and I noticed that this
function doesn't work quite right -- accessing cur->bc_ino depends on
the ROOT_IN_INODE flag, not LONG_PTRS.  Fix that and the parentheses
isssue.  While we're at it, remove the piece that accesses cur->bc_ag,
because block 0 of an AG is never part of a btree.

Note: This changes the btree scrubber tracepoints behavior -- if the
cursor has no buffer for a certain level, it will always report
NULLFSBLOCK.  It is assumed that anyone tracing the online fsck code
will also be tracing xchk_start/xchk_done or otherwise be aware of what
exactly is being scrubbed.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

The for_each_perag*() set of macros are hacky in that some (i.e.
those based on sb_agcount) rely on the assumption that perag
iteration terminates naturally with a NULL perag at the specified
end_agno. Others allow for the final AG to have a valid perag and
require the calling function to clean up any potential leftover
xfs_perag reference on termination of the loop.

Aside from providing a subtly inconsistent interface, the former
variant is racy with growfs because growfs can create discoverable
post-eofs perags before the final superblock update that completes
the grow operation and increases sb_agcount. This leads to the
following assert failure (reproduced by xfs/104) in the perag free
path during unmount:

 XFS: Assertion failed: atomic_read(&pag->pag_ref) == 0, file: fs/xfs/libxfs/xfs_ag.c, line: 195

This occurs because one of the many for_each_perag() loops in the
code that is expected to terminate with a NULL pag (and thus has no
post-loop xfs_perag_put() check) raced with a growfs and found a
non-NULL post-EOFS perag, but terminated naturally based on the
end_agno check without releasing the post-EOFS perag.

Rework the iteration logic to lift the agno check from the main for
loop conditional to the iteration helper function. The for loop now
purely terminates on a NULL pag and xfs_perag_next() avoids taking a
reference to any perag beyond end_agno in the first place.

Fixes: f250eed ("xfs: make for_each_perag... a first class citizen")
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

The for_each_perag_from() iteration macro relies on sb_agcount to
process every perag currently within EOFS from a given starting
point. It's perfectly valid to have perag structures beyond
sb_agcount, however, such as if a growfs is in progress. If a perag
loop happens to race with growfs in this manner, it will actually
attempt to process the post-EOFS perag where ->pag_agno ==
sb_agcount. This is reproduced by xfs/104 and manifests as the
following assert failure in superblock write verifier context:

 XFS: Assertion failed: agno < mp->m_sb.sb_agcount, file: fs/xfs/libxfs/xfs_types.c, line: 22

Update the corresponding macro to only process perags that are
within the current sb_agcount.

Fixes: 58d43a7 ("xfs: pass perags around in fsmap data dev functions")
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Rename the next_agno variable to be consistent across the several
iteration macros and shorten line length.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Fold the loop iteration logic into a helper in preparation for
further fixups. No functional change in this patch.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

coccicheck complains about the use of snprintf() in sysfs show functions.

Fix the coccicheck warning:
WARNING: use scnprintf or sprintf.

Use sysfs_emit instead of scnprintf or sprintf makes more sense.

Signed-off-by: Qing Wang <wangqing@vivo.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Remove the few leftover instances of the xfs_dinode_t typedef.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>