Use proper abbreviation of the 'offset in folio' in the variable name,
same as we have in accessors.c.
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
The variables calculating where to jump next are using mixed in types
which requires some conversions on the instruction level. Using 'u32'
removes one call to 'movslq', making the main loop shorter.
This complements type conversion done in a724f313f8 ("btrfs: do
unsigned integer division in the extent buffer binary search loop")
Signed-off-by: David Sterba <dsterba@suse.com>
In the main search loop the variable 'oil' (offset in folio) is set
twice, one duplicated when the key fits completely to the contiguous
range. We can remove it and while it's just a simple calculation, the
binary search loop is executed many times so micro optimizations add up.
The code size is reduced by 64 bytes on release config, the loop is
reorganized a bit and a few instructions shorter.
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
That parameter was introduced by commit b9fab919b7 ("Btrfs: avoid
sleeping in verify_parent_transid while atomic").
At that time we needed to lock the extent buffer range inside the io tree
to avoid content changes, thus it could sleep.
But that behavior is no longer there, as later commit 9e2aff90fc
("btrfs: stop using lock_extent in btrfs_buffer_uptodate") dropped the
io tree lock.
We can remove the @atomic parameter safely now.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
read_extent_buffer_pages_nowait() returns immediately when an extent
buffer is already marked uptodate. On that cache-hit path,
the caller supplied btrfs_tree_parent_check is not re-run.
This can let read_tree_root_path() accept a cached tree block whose
actual header level/owner does not match the expected value derived from
the parent.
E.g. a corrupted root item that points to a tree block which doesn't
even belong to that root, and has mismatching level/owner.
But that tree block is already read and cached, later the corrupted tree
root got read from disk and hit the cached tree block.
Fix this by re-validating cached extent buffers against the supplied
btrfs_tree_parent_check on the uptodate path, and make
read_tree_root_path() pass its check to btrfs_buffer_uptodate().
This makes cache hits and fresh reads follow the same tree-parent
verification rules, and turns the corruption into a read failure instead
of constructing an inconsistent root object.
Signed-off-by: ZhengYuan Huang <gality369@gmail.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
[ Resolve the conflict with extent_buffer_uptodate() helper, handle
transid mismatch case ]
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Add a btrfs_search_slot_restart tracepoint that fires at each restart
site in btrfs_search_slot(), recording the root, tree level, and
reason for the restart. This enables tracking search slot restarts
which contribute to COW amplification under memory pressure.
The four restart reasons are:
- write_lock: insufficient write lock level, need to restart with
higher lock
- setup_nodes: node setup returned -EAGAIN
- slot_zero: insertion at slot 0 requires higher write lock level
- read_block: read_block_for_search returned -EAGAIN (block not
cached or lock contention)
COW counts are already tracked by the existing trace_btrfs_cow_block()
tracepoint. The per-restart-site tracepoint avoids counter overhead
in the critical path when tracepoints are disabled, and provides
richer per-event information that bpftrace scripts can aggregate into
counts, histograms, and per-root breakdowns.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Leo Martins <loemra.dev@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Inhibit writeback on COW'd extent buffers for the lifetime of the
transaction handle, preventing background writeback from setting
BTRFS_HEADER_FLAG_WRITTEN and causing unnecessary re-COW.
COW amplification occurs when background writeback flushes an extent
buffer that a transaction handle is still actively modifying. When
lock_extent_buffer_for_io() transitions a buffer from dirty to
writeback, it sets BTRFS_HEADER_FLAG_WRITTEN, marking the block as
having been persisted to disk at its current bytenr. Once WRITTEN is
set, should_cow_block() must either COW the block again or overwrite
it in place, both of which are unnecessary overhead when the buffer
is still being modified by the same handle that allocated it. By
inhibiting background writeback on actively-used buffers, WRITTEN is
never set while a transaction handle holds a reference to the buffer,
avoiding this overhead entirely.
Add an atomic_t writeback_inhibitors counter to struct extent_buffer,
which fits in an existing 6-byte hole without increasing struct size.
When a buffer is COW'd in btrfs_force_cow_block(), call
btrfs_inhibit_eb_writeback() to store the eb in the transaction
handle's writeback_inhibited_ebs xarray (keyed by eb->start), take a
reference, and increment writeback_inhibitors. The function handles
dedup (same eb inhibited twice by the same handle) and replacement
(different eb at the same logical address). Allocation failure is
graceful: the buffer simply falls back to the pre-existing behavior
where it may be written back and re-COW'd.
Also inhibit writeback in should_cow_block() when COW is skipped,
so that every transaction handle that reuses an already-COW'd buffer
also inhibits its writeback. Without this, if handle A COWs a block
and inhibits it, and handle B later reuses the same block without
inhibiting, handle A's uninhibit on end_transaction leaves the buffer
unprotected while handle B is still using it. This ensures all handles
that access a COW'd buffer contribute to the inhibitor count, and the
buffer remains protected until the last handle releases it.
In lock_extent_buffer_for_io(), when writeback_inhibitors is non-zero
and the writeback mode is WB_SYNC_NONE, skip the buffer. WB_SYNC_NONE
is used by the VM flusher threads for background and periodic
writeback, which are the only paths that cause COW amplification by
opportunistically writing out dirty extent buffers mid-transaction.
Skipping these is safe because the buffers remain dirty in the page
cache and will be written out at transaction commit time.
WB_SYNC_ALL must always proceed regardless of writeback_inhibitors.
This is required for correctness in the fsync path: btrfs_sync_log()
writes log tree blocks via filemap_fdatawrite_range() (WB_SYNC_ALL)
while the transaction handle that inhibited those same blocks is still
active. Without the WB_SYNC_ALL bypass, those inhibited log tree
blocks would be silently skipped, resulting in an incomplete log on
disk and corruption on replay. btrfs_write_and_wait_transaction()
also uses WB_SYNC_ALL via filemap_fdatawrite_range(); for that path,
inhibitors are already cleared beforehand, but the bypass ensures
correctness regardless.
Uninhibit in __btrfs_end_transaction() before atomic_dec(num_writers)
to prevent a race where the committer proceeds while buffers are still
inhibited. Also uninhibit in btrfs_commit_transaction() before writing
and in cleanup_transaction() for the error path.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Sun YangKai <sunk67188@gmail.com>
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Leo Martins <loemra.dev@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We have several functions with parameters defined as booleans but then we
have callers passing integers, 0 or 1, instead of false and true. While
this isn't a bug since 0 and 1 are converted to false and true, it is odd
and less readable. Change the callers to pass true and false literals
instead.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We have several places that call extent_buffer_uptodate() after reading a
tree block with read_tree_block(), but that is redundant since we already
call extent_buffer_uptodate() in the call chain of read_tree_block():
read_tree_block()
btrfs_read_extent_buffer()
read_extent_buffer_pages()
returns -EIO if extent_buffer_uptodate() returns false
So remove those redundant checks.
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In many places we have pattern:
ret = ...;
return ret;
This can be simplified to a direct return, removing 'ret' if not
otherwise needed. The places in self tests are not converted so we can
add more test cases without changing surrounding code
(extent-map-tests.c:test_case_4()).
Signed-off-by: David Sterba <dsterba@suse.com>
Replace open-coded if/else blocks with the boolean directly and introduce
local const bool variables, making the code shorter and easier to read.
Signed-off-by: Sun YangKai <sunk67188@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Replace integer literals 0/1 with true/false when calling
btrfs_inc_ref() and btrfs_dec_ref() to make the code self-documenting
and avoid mixing bool/integer types.
Signed-off-by: Sun YangKai <sunk67188@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When btrfs_del_items() empties a leaf, it deletes the leaf unless it's
the root node. For the root leaf case, the code used to reset its level
to 0 via btrfs_set_header_level(). This is redundant as leaf nodes
always have level == 0.
Remove the unnecessary level assignment and invert the conditional to
handle only the non-root leaf deletion. The root leaf is correctly left
as-is.
Signed-off-by: Sun YangKai <sunk67188@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
After releasing the path in btrfs_next_old_leaf(), we need to re-check
the leaf because a balance operation may have added items or removed the
last item. The original code handled this with two separate conditional
blocks, the second marked with a lengthy comment explaining a "missed
case".
Merge these two blocks into a single logical structure that handles both
scenarios more clearly.
Also update the comment to be more concise and accurate, incorporating the
explanation directly into the main block rather than a separate annotation.
Signed-off-by: Sun YangKai <sunk67188@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Instead of incrementing refcount on 'left' node when it's referenced by
path, simply transfer ownership to path and set left to NULL. This
eliminates:
- Unnecessary refcount increment/decrement operations
- Redundant conditional checks for left node cleanup
The path now consistently owns the left node reference when used.
Signed-off-by: Sun YangKai <sunk67188@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The balance_level() function is overly long and contains a cold code path
that handles promoting a child node to root when the root has only one item.
This code has distinct logic that is clearer and more maintainable when
isolated in its own function.
Signed-off-by: Sun YangKai <sunk67188@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Many fields of struct btrfs_path are used as booleans but their type is
an unsigned int (of one 1 bit width to save space). Change the type to
bool keeping the :1 suffix so that they combine with the previous u8
fields in order to save space. This makes the code more clear by using
explicit true/false and more in line with the preferred style, preserving
the size of the structure.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There's no need to update the local variable 'check_skip' to false inside
the critical section delimited by the lock of the current node, so do it
after unlocking the node.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If we try to push an item count from the right leaf that is greater than
the number of items in the leaf, we just emit a warning. This should
never happen but if it does we get an underflow in the new number of
items in the right leaf and chaos follows from it. So replace the warning
with proper error handling, by aborting the transaction and returning
-EUCLEAN, and proper logging by using btrfs_crit() instead of WARN(),
which gives us proper formatting and information about the filesystem.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The 'right' variable points to path->nodes[0] and path->nodes[0] is never
changed, but some places use 'right' while others refer to path->nodes[0].
Update all sites to use 'right' as not only it's shorter it's also easier
to reason since it means the right leaf and avoids any confusion with the
sibling left leaf.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We have already called btrfs_clear_buffer_dirty() against the left leaf in
the code above:
btrfs_set_header_nritems(left, left_nritems);
if (left_nritems)
btrfs_mark_buffer_dirty(trans, left);
else
btrfs_clear_buffer_dirty(trans, left);
So remove the second check for a 0 number of items in the left leaf and
calling again btrfs_clear_buffer_dirty() against the left leaf.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The 'left' variable points to path->nodes[0] and path->nodes[0] is never
changed, but some places use 'left' while others refer to path->nodes[0].
Update all sites to use 'left' as not only it's shorter it's also easier
to reason since it means the left leaf and avoids any confusion with the
sibling right leaf.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
It's not expected to get a data size less than the leaf's free space,
which would lead to a leaf dump and BUG(), so tag the if statement's
expression as unlikely, hinting the compiler to potentially generate
better code.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The call to btrfs_del_leaf() can only return an error (negative value) or
zero (success). If we didn't get an error then 'ret' is zero, so it's
pointless to set it to zero again.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If the call to btrfs_del_leaf() fails we return without decrementing the
extra ref we took on the leaf, therefore leaking it. Fix this by ensuring
we drop the ref count before returning the error.
Fixes: 751a27615d ("btrfs: do not BUG_ON() on tree mod log failures at btrfs_del_ptr()")
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There's no point in setting 'data_end' to 'old_data' as we don't use it
afterwards. So remove the redundant assignment which was never needed
and added when the function was first added in commit 6567e837df
("Btrfs: early work to file_write in big extents").
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Change all locations that print a key to use the new macros to print
them in order to ensure a consistent style and avoid repetitive code.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The unlikely() annotation is a static prediction hint that compiler may
use to reorder code out of hot path. We use it elsewhere (namely
tree-checker.c) for error branches that almost never happen.
Transaction abort is one such error, the btrfs_abort_transaction()
inlines code to check the state and print a warning, this ought to be
out of the hot path.
The most common pattern is when transaction abort is called after
checking a return value and the control flow leads to a quick return.
In other cases it may not be necessary to add unlikely() e.g. when the
function returns anyway or the control flow is not changed noticeably.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The unlikely() annotation is a static prediction hint that compiler may
use to reorder code out of hot path. We use it elsewhere (namely
tree-checker.c) for error branches that almost never happen, where
EUCLEAN (a corruption) is one of them.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
It's quite hard and unreadable the way the rule checks are organized in
should_cow_block(). We have a single if statement that returns 0 (false)
and it checks several conditions, with one them being a negated compound
condition which is particularly hard to reason immediately.
Improve on this by using multiple if statements, each checking a single
condition and returning immediately. Also change the return type from an
integer to a boolean, since all we need is to return true or false.
At least on x86_64 with Debian's gcc 14.2.0-19, this also reduces the
object code size by 64 bytes.
Before this change:
$ size fs/btrfs/btrfs.ko
text data bss dec hex filename
1913327 161567 15592 2090486 1fe5f6 fs/btrfs/btrfs.ko
After this change:
$ size fs/btrfs/btrfs.ko
text data bss dec hex filename
1913263 161567 15592 2090422 1fe5b6 fs/btrfs/btrfs.ko
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We have several sanity checks when inserting or extending items in a btree
that verify we didn't overflow the leaf or access a slot beyond the last
one. These are cases that are never expected to be hit so mark them as
unlikely, allowing the compiler to potentially generate better code.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We expect that after attempting to read an extent buffer we had no errors
therefore the extent buffer is up to date, so mark the checks for a not up
to date extent buffer as unlikely and allow the compiler to pontentially
generate better code.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We're almost done cleaning misused int/bool parameters. Convert a bunch
of them, found by manual grepping. Note that btrfs_sync_fs() needs an
int as it's mandated by the struct super_operations prototype.
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
The token versions of set/get accessors will be removed, use the normal
helpers. The btrfs_item members use that interface the most but there
are no real benefits anymore.
This reduces stack consumption on x86_64 release config:
setup_items_for_insert -32 (144 -> 112)
__push_leaf_left -32 (176 -> 144)
btrfs_extend_item -16 (104 -> 88)
copy_for_split -32 (144 -> 112)
btrfs_del_items -16 (144 -> 128)
btrfs_truncate_item -24 (152 -> 128)
__push_leaf_right -24 (168 -> 144)
and module size:
text data bss dec hex filename
1463615 115665 16088 1595368 1857e8 pre/btrfs.ko
1463413 115665 16088 1595166 18571e post/btrfs.ko
DELTA: -202
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If we failed to insert the tree mod log operation, we are not removing the
dirty status from the allocated and dirtied extent buffer before we free
it. Removing the dirty status is needed for several reasons such as to
adjust the fs_info->dirty_metadata_bytes counter and remove the dirty
status from the respective folios. So add the missing call to
btrfs_clear_buffer_dirty().
Fixes: f61aa7ba08 ("btrfs: do not BUG_ON() on tree mod log failure at insert_new_root()")
CC: stable@vger.kernel.org # 6.6+
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Commit 323ac95bce ("Btrfs: don't read leaf blocks containing only
checksums during truncate") changed the condition from `level == 0` to
`level == path->lowest_level`, while its original purpose was just to do
some leaf node handling (calling btrfs_item_key_to_cpu()) and skip some
code that doesn't fit leaf nodes.
After changing the condition, the code path:
1. Also handles the non-leaf nodes when path->lowest_level is nonzero,
which is wrong. However btrfs_search_forward() is never called with a
nonzero path->lowest_level, which makes this bug not found before.
2. Makes the later if block with the same condition, which was originally
used to handle non-leaf node (calling btrfs_node_key_to_cpu()) when
lowest_level is not zero, dead code.
Since btrfs_search_forward() is never called for a path with a
lowest_level different from zero, just completely remove the partial
support for a non-zero lowest_level, simplifying a bit the code, and
assert that lowest_level is zero at the start of the function.
Suggested-by: Qu Wenruo <wqu@suse.com>
Fixes: 323ac95bce ("Btrfs: don't read leaf blocks containing only checksums during truncate")
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Sun YangKai <sunk67188@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Instead of using a bare atomic, use the refcount_t type, which despite
being a structure that contains only an atomic, has an API that checks
for underflows and other hazards. This doesn't change the size of the
extent_buffer structure.
This removes the need to do things like this:
WARN_ON(atomic_read(&eb->refs) == 0);
if (atomic_dec_and_test(&eb->refs)) {
(...)
}
And do just:
if (refcount_dec_and_test(&eb->refs)) {
(...)
}
Since refcount_dec_and_test() already triggers a warning when we decrement
a ref count that has a value of 0 (or below zero).
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Unify naming of return value to the preferred way, move the variable to
the closest scope.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Unify naming of return value to the preferred way, move the variable to
the closest scope.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Another batch of pointer parameter constifications. This is for clarity
and minor addition to type safety. There are no observable effects in the
assembly code and .ko measured on release config.
Signed-off-by: David Sterba <dsterba@suse.com>
If we find an unexpected generation for the extent buffer we are cloning
at btrfs_copy_root(), we just WARN_ON() and don't error out and abort the
transaction, meaning we allow to persist metadata with an unexpected
generation. Instead of warning only, abort the transaction and return
-EUCLEAN.
CC: stable@vger.kernel.org # 6.1+
Reviewed-by: Daniel Vacek <neelx@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Instead of having a common btrfs_abort_transaction() call for when any of
the two btrfs_inc_ref() calls fail, move the btrfs_abort_transaction() to
happen immediately after each one of the calls, so that when analyzing a
stack trace with a transaction abort we know which call failed.
Reviewed-by: Daniel Vacek <neelx@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Move path slot assignment before the condition check to prevent
duplicate assignment. Previously, the slot was set both inside and after
the 'slot >= nritems' block with no change in its value, which is
unnecessary.
Signed-off-by: Sun YangKai <sunk67188@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The 'found_key' variable was only used to temporarily store the found key
before copying it to 'min_key' at the end of the function when returning
success.
Eliminate the 'found_key' variable, and directly store the key into
'min_key' at the exact loop exit points where ret=0 is set, maintaining
identical functionality.
Signed-off-by: Sun YangKai <sunk67188@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The most trivial pattern for the auto freeing when the variable is
declared with the macro and the final btrfs_free_path() is removed.
There are almost none goto -> return conversions and there's no other
function cleanup.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When COWing a relocation tree path, at relocation.c:replace_path(), we
can trigger a lockdep splat while we are in the btrfs_search_slot() call
against the relocation root. This happens in that callchain at
ctree.c:read_block_for_search() when we happen to find a child extent
buffer already loaded through the fs tree with a lockdep class set to
the fs tree. So when we attempt to lock that extent buffer through a
relocation tree we have to reset the lockdep class to the class for a
relocation tree, since a relocation tree has extent buffers that used
to belong to a fs tree and may currently be already loaded (we swap
extent buffers between the two trees at the end of replace_path()).
However we are missing calls to btrfs_maybe_reset_lockdep_class() to reset
the lockdep class at ctree.c:read_block_for_search() before we read lock
an extent buffer, just like we did for btrfs_search_slot() in commit
b40130b23c ("btrfs: fix lockdep splat with reloc root extent buffers").
So add the missing btrfs_maybe_reset_lockdep_class() calls before the
attempts to read lock an extent buffer at ctree.c:read_block_for_search().
The lockdep splat was reported by syzbot and it looks like this:
======================================================
WARNING: possible circular locking dependency detected
6.13.0-rc5-syzkaller-00163-gab75170520d4 #0 Not tainted
------------------------------------------------------
syz.0.0/5335 is trying to acquire lock:
ffff8880545dbc38 (btrfs-tree-01){++++}-{4:4}, at: btrfs_tree_read_lock_nested+0x2f/0x250 fs/btrfs/locking.c:146
but task is already holding lock:
ffff8880545dba58 (btrfs-treloc-02/1){+.+.}-{4:4}, at: btrfs_tree_lock_nested+0x2f/0x250 fs/btrfs/locking.c:189
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (btrfs-treloc-02/1){+.+.}-{4:4}:
reacquire_held_locks+0x3eb/0x690 kernel/locking/lockdep.c:5374
__lock_release kernel/locking/lockdep.c:5563 [inline]
lock_release+0x396/0xa30 kernel/locking/lockdep.c:5870
up_write+0x79/0x590 kernel/locking/rwsem.c:1629
btrfs_force_cow_block+0x14b3/0x1fd0 fs/btrfs/ctree.c:660
btrfs_cow_block+0x371/0x830 fs/btrfs/ctree.c:755
btrfs_search_slot+0xc01/0x3180 fs/btrfs/ctree.c:2153
replace_path+0x1243/0x2740 fs/btrfs/relocation.c:1224
merge_reloc_root+0xc46/0x1ad0 fs/btrfs/relocation.c:1692
merge_reloc_roots+0x3b3/0x980 fs/btrfs/relocation.c:1942
relocate_block_group+0xb0a/0xd40 fs/btrfs/relocation.c:3754
btrfs_relocate_block_group+0x77d/0xd90 fs/btrfs/relocation.c:4087
btrfs_relocate_chunk+0x12c/0x3b0 fs/btrfs/volumes.c:3494
__btrfs_balance+0x1b0f/0x26b0 fs/btrfs/volumes.c:4278
btrfs_balance+0xbdc/0x10c0 fs/btrfs/volumes.c:4655
btrfs_ioctl_balance+0x493/0x7c0 fs/btrfs/ioctl.c:3670
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:906 [inline]
__se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #1 (btrfs-tree-01/1){+.+.}-{4:4}:
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
down_write_nested+0xa2/0x220 kernel/locking/rwsem.c:1693
btrfs_tree_lock_nested+0x2f/0x250 fs/btrfs/locking.c:189
btrfs_init_new_buffer fs/btrfs/extent-tree.c:5052 [inline]
btrfs_alloc_tree_block+0x41c/0x1440 fs/btrfs/extent-tree.c:5132
btrfs_force_cow_block+0x526/0x1fd0 fs/btrfs/ctree.c:573
btrfs_cow_block+0x371/0x830 fs/btrfs/ctree.c:755
btrfs_search_slot+0xc01/0x3180 fs/btrfs/ctree.c:2153
btrfs_insert_empty_items+0x9c/0x1a0 fs/btrfs/ctree.c:4351
btrfs_insert_empty_item fs/btrfs/ctree.h:688 [inline]
btrfs_insert_inode_ref+0x2bb/0xf80 fs/btrfs/inode-item.c:330
btrfs_rename_exchange fs/btrfs/inode.c:7990 [inline]
btrfs_rename2+0xcb7/0x2b90 fs/btrfs/inode.c:8374
vfs_rename+0xbdb/0xf00 fs/namei.c:5067
do_renameat2+0xd94/0x13f0 fs/namei.c:5224
__do_sys_renameat2 fs/namei.c:5258 [inline]
__se_sys_renameat2 fs/namei.c:5255 [inline]
__x64_sys_renameat2+0xce/0xe0 fs/namei.c:5255
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #0 (btrfs-tree-01){++++}-{4:4}:
check_prev_add kernel/locking/lockdep.c:3161 [inline]
check_prevs_add kernel/locking/lockdep.c:3280 [inline]
validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
__lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
down_read_nested+0xb5/0xa50 kernel/locking/rwsem.c:1649
btrfs_tree_read_lock_nested+0x2f/0x250 fs/btrfs/locking.c:146
btrfs_tree_read_lock fs/btrfs/locking.h:188 [inline]
read_block_for_search+0x718/0xbb0 fs/btrfs/ctree.c:1610
btrfs_search_slot+0x1274/0x3180 fs/btrfs/ctree.c:2237
replace_path+0x1243/0x2740 fs/btrfs/relocation.c:1224
merge_reloc_root+0xc46/0x1ad0 fs/btrfs/relocation.c:1692
merge_reloc_roots+0x3b3/0x980 fs/btrfs/relocation.c:1942
relocate_block_group+0xb0a/0xd40 fs/btrfs/relocation.c:3754
btrfs_relocate_block_group+0x77d/0xd90 fs/btrfs/relocation.c:4087
btrfs_relocate_chunk+0x12c/0x3b0 fs/btrfs/volumes.c:3494
__btrfs_balance+0x1b0f/0x26b0 fs/btrfs/volumes.c:4278
btrfs_balance+0xbdc/0x10c0 fs/btrfs/volumes.c:4655
btrfs_ioctl_balance+0x493/0x7c0 fs/btrfs/ioctl.c:3670
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:906 [inline]
__se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
other info that might help us debug this:
Chain exists of:
btrfs-tree-01 --> btrfs-tree-01/1 --> btrfs-treloc-02/1
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(btrfs-treloc-02/1);
lock(btrfs-tree-01/1);
lock(btrfs-treloc-02/1);
rlock(btrfs-tree-01);
*** DEADLOCK ***
8 locks held by syz.0.0/5335:
#0: ffff88801e3ae420 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write_file+0x5e/0x200 fs/namespace.c:559
#1: ffff888052c760d0 (&fs_info->reclaim_bgs_lock){+.+.}-{4:4}, at: __btrfs_balance+0x4c2/0x26b0 fs/btrfs/volumes.c:4183
#2: ffff888052c74850 (&fs_info->cleaner_mutex){+.+.}-{4:4}, at: btrfs_relocate_block_group+0x775/0xd90 fs/btrfs/relocation.c:4086
#3: ffff88801e3ae610 (sb_internal#2){.+.+}-{0:0}, at: merge_reloc_root+0xf11/0x1ad0 fs/btrfs/relocation.c:1659
#4: ffff888052c76470 (btrfs_trans_num_writers){++++}-{0:0}, at: join_transaction+0x405/0xda0 fs/btrfs/transaction.c:288
#5: ffff888052c76498 (btrfs_trans_num_extwriters){++++}-{0:0}, at: join_transaction+0x405/0xda0 fs/btrfs/transaction.c:288
#6: ffff8880545db878 (btrfs-tree-01/1){+.+.}-{4:4}, at: btrfs_tree_lock_nested+0x2f/0x250 fs/btrfs/locking.c:189
#7: ffff8880545dba58 (btrfs-treloc-02/1){+.+.}-{4:4}, at: btrfs_tree_lock_nested+0x2f/0x250 fs/btrfs/locking.c:189
stack backtrace:
CPU: 0 UID: 0 PID: 5335 Comm: syz.0.0 Not tainted 6.13.0-rc5-syzkaller-00163-gab75170520d4 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2074
check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2206
check_prev_add kernel/locking/lockdep.c:3161 [inline]
check_prevs_add kernel/locking/lockdep.c:3280 [inline]
validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
__lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
down_read_nested+0xb5/0xa50 kernel/locking/rwsem.c:1649
btrfs_tree_read_lock_nested+0x2f/0x250 fs/btrfs/locking.c:146
btrfs_tree_read_lock fs/btrfs/locking.h:188 [inline]
read_block_for_search+0x718/0xbb0 fs/btrfs/ctree.c:1610
btrfs_search_slot+0x1274/0x3180 fs/btrfs/ctree.c:2237
replace_path+0x1243/0x2740 fs/btrfs/relocation.c:1224
merge_reloc_root+0xc46/0x1ad0 fs/btrfs/relocation.c:1692
merge_reloc_roots+0x3b3/0x980 fs/btrfs/relocation.c:1942
relocate_block_group+0xb0a/0xd40 fs/btrfs/relocation.c:3754
btrfs_relocate_block_group+0x77d/0xd90 fs/btrfs/relocation.c:4087
btrfs_relocate_chunk+0x12c/0x3b0 fs/btrfs/volumes.c:3494
__btrfs_balance+0x1b0f/0x26b0 fs/btrfs/volumes.c:4278
btrfs_balance+0xbdc/0x10c0 fs/btrfs/volumes.c:4655
btrfs_ioctl_balance+0x493/0x7c0 fs/btrfs/ioctl.c:3670
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:906 [inline]
__se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1ac6985d29
Code: ff ff c3 (...)
RSP: 002b:00007f1ac63fe038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f1ac6b76160 RCX: 00007f1ac6985d29
RDX: 0000000020000180 RSI: 00000000c4009420 RDI: 0000000000000007
RBP: 00007f1ac6a01b08 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f1ac6b76160 R15: 00007fffda145a88
</TASK>
Reported-by: syzbot+63913e558c084f7f8fdc@syzkaller.appspotmail.com
Link: https://lore.kernel.org/linux-btrfs/677b3014.050a0220.3b53b0.0064.GAE@google.com/
Fixes: 99785998ed ("btrfs: reduce lock contention when eb cache miss for btree search")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If the stripe extent we want to delete starts before the range we want to
delete and ends after the range we want to delete we're punching a
hole in the stripe extent:
|--- RAID Stripe Extent ---|
| keep |--- drop ---| keep |
This means we need to a) truncate the existing item and b)
create a second item for the remaining range.
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The ctree module is about the implementation of the btree data structure
and not a place holder for generic filesystem things like the csum
algorithm details. Move the functions related to the csum algorithm
details away from ctree.c and into fs.c, which is a far better place for
them. Also fix missing punctuation in comments and change one multiline
comment to a single line comment since everything fits in under 80
characters.
For some reason this also slightly reduces the module's size.
Before this change:
$ size fs/btrfs/btrfs.ko
text data bss dec hex filename
1782126 161045 16920 1960091 1de89b fs/btrfs/btrfs.ko
After this change:
$ size fs/btrfs/btrfs.ko
text data bss dec hex filename
1782094 161045 16920 1960059 1de87b fs/btrfs/btrfs.ko
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
