btrfs: abort transaction on generation mismatch when marking eb as dirty

[ Upstream commit 50564b651d01c19ce732819c5b3c3fd60707188e ]

When marking an extent buffer as dirty, at btrfs_mark_buffer_di

btrfs: abort transaction on generation mismatch when marking eb as dirty

[ Upstream commit 50564b651d01c19ce732819c5b3c3fd60707188e ]

When marking an extent buffer as dirty, at btrfs_mark_buffer_dirty(),
we check if its generation matches the running transaction and if not we
just print a warning. Such mismatch is an indicator that something really
went wrong and only printing a warning message (and stack trace) is not
enough to prevent a corruption. Allowing a transaction to commit with such
an extent buffer will trigger an error if we ever try to read it from disk
due to a generation mismatch with its parent generation.

So abort the current transaction with -EUCLEAN if we notice a generation
mismatch. For this we need to pass a transaction handle to
btrfs_mark_buffer_dirty() which is always available except in test code,
in which case we can pass NULL since it operates on dummy extent buffers
and all test roots have a single node/leaf (root node at level 0).

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

show more ...

btrfs: fix unwritten extent buffer after snapshotting a new subvolume

When creating a snapshot of a subvolume that was created in the current
transaction, we can end up not persisting a dirty extent

btrfs: fix unwritten extent buffer after snapshotting a new subvolume

When creating a snapshot of a subvolume that was created in the current
transaction, we can end up not persisting a dirty extent buffer that is
referenced by the snapshot, resulting in IO errors due to checksum failures
when trying to read the extent buffer later from disk. A sequence of steps
that leads to this is the following:

1) At ioctl.c:create_subvol() we allocate an extent buffer, with logical
address 36007936, for the leaf/root of a new subvolume that has an ID
of 291. We mark the extent buffer as dirty, and at this point the
subvolume tree has a single node/leaf which is also its root (level 0);

2) We no longer commit the transaction used to create the subvolume at
create_subvol(). We used to, but that was recently removed in
commit 1b53e51a4a8f ("btrfs: don't commit transaction for every subvol
create");

3) The transaction used to create the subvolume has an ID of 33, so the
extent buffer 36007936 has a generation of 33;

4) Several updates happen to subvolume 291 during transaction 33, several
files created and its tree height changes from 0 to 1, so we end up with
a new root at level 1 and the extent buffer 36007936 is now a leaf of
that new root node, which is extent buffer 36048896.

The commit root remains as 36007936, since we are still at transaction
33;

5) Creation of a snapshot of subvolume 291, with an ID of 292, starts at
ioctl.c:create_snapshot(). This triggers a commit of transaction 33 and
we end up at transaction.c:create_pending_snapshot(), in the critical
section of a transaction commit.

There we COW the root of subvolume 291, which is extent buffer 36048896.
The COW operation returns extent buffer 36048896, since there's no need
to COW because the extent buffer was created in this transaction and it
was not written yet.

The we call btrfs_copy_root() against the root node 36048896. During
this operation we allocate a new extent buffer to turn into the root
node of the snapshot, copy the contents of the root node 36048896 into
this snapshot root extent buffer, set the owner to 292 (the ID of the
snapshot), etc, and then we call btrfs_inc_ref(). This will create a
delayed reference for each leaf pointed by the root node with a
reference root of 292 - this includes a reference for the leaf
36007936.

After that we set the bit BTRFS_ROOT_FORCE_COW in the root's state.

Then we call btrfs_insert_dir_item(), to create the directory entry in
in the tree of subvolume 291 that points to the snapshot. This ends up
needing to modify leaf 36007936 to insert the respective directory
items. Because the bit BTRFS_ROOT_FORCE_COW is set for the root's state,
we need to COW the leaf. We end up at btrfs_force_cow_block() and then
at update_ref_for_cow().

At update_ref_for_cow() we call btrfs_block_can_be_shared() which
returns false, despite the fact the leaf 36007936 is shared - the
subvolume's root and the snapshot's root point to that leaf. The
reason that it incorrectly returns false is because the commit root
of the subvolume is extent buffer 36007936 - it was the initial root
of the subvolume when we created it. So btrfs_block_can_be_shared()
which has the following logic:

int btrfs_block_can_be_shared(struct btrfs_root *root,
struct extent_buffer *buf)
{
if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
buf != root->node && buf != root->commit_root &&
(btrfs_header_generation(buf) <=
btrfs_root_last_snapshot(&root->root_item) ||
btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
return 1;

return 0;
}

Returns false (0) since 'buf' (extent buffer 36007936) matches the
root's commit root.

As a result, at update_ref_for_cow(), we don't check for the number
of references for extent buffer 36007936, we just assume it's not
shared and therefore that it has only 1 reference, so we set the local
variable 'refs' to 1.

Later on, in the final if-else statement at update_ref_for_cow():

static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct extent_buffer *buf,
struct extent_buffer *cow,
int *last_ref)
{
(...)
if (refs > 1) {
(...)
} else {
(...)
btrfs_clear_buffer_dirty(trans, buf);
*last_ref = 1;
}
}

So we mark the extent buffer 36007936 as not dirty, and as a result
we don't write it to disk later in the transaction commit, despite the
fact that the snapshot's root points to it.

Attempting to access the leaf or dumping the tree for example shows
that the extent buffer was not written:

$ btrfs inspect-internal dump-tree -t 292 /dev/sdb
btrfs-progs v6.2.2
file tree key (292 ROOT_ITEM 33)
node 36110336 level 1 items 2 free space 119 generation 33 owner 292
node 36110336 flags 0x1(WRITTEN) backref revision 1
checksum stored a8103e3e
checksum calced a8103e3e
fs uuid 90c9a46f-ae9f-4626-9aff-0cbf3e2e3a79
chunk uuid e8c9c885-78f4-4d31-85fe-89e5f5fd4a07
key (256 INODE_ITEM 0) block 36007936 gen 33
key (257 EXTENT_DATA 0) block 36052992 gen 33
checksum verify failed on 36007936 wanted 0x00000000 found 0x86005f29
checksum verify failed on 36007936 wanted 0x00000000 found 0x86005f29
total bytes 107374182400
bytes used 38572032
uuid 90c9a46f-ae9f-4626-9aff-0cbf3e2e3a79

The respective on disk region is full of zeroes as the device was
trimmed at mkfs time.

Obviously 'btrfs check' also detects and complains about this:

$ btrfs check /dev/sdb
Opening filesystem to check...
Checking filesystem on /dev/sdb
UUID: 90c9a46f-ae9f-4626-9aff-0cbf3e2e3a79
generation: 33 (33)
[1/7] checking root items
[2/7] checking extents
checksum verify failed on 36007936 wanted 0x00000000 found 0x86005f29
checksum verify failed on 36007936 wanted 0x00000000 found 0x86005f29
checksum verify failed on 36007936 wanted 0x00000000 found 0x86005f29
bad tree block 36007936, bytenr mismatch, want=36007936, have=0
owner ref check failed [36007936 4096]
ERROR: errors found in extent allocation tree or chunk allocation
[3/7] checking free space tree
[4/7] checking fs roots
checksum verify failed on 36007936 wanted 0x00000000 found 0x86005f29
checksum verify failed on 36007936 wanted 0x00000000 found 0x86005f29
checksum verify failed on 36007936 wanted 0x00000000 found 0x86005f29
bad tree block 36007936, bytenr mismatch, want=36007936, have=0
The following tree block(s) is corrupted in tree 292:
tree block bytenr: 36110336, level: 1, node key: (256, 1, 0)
root 292 root dir 256 not found
ERROR: errors found in fs roots
found 38572032 bytes used, error(s) found
total csum bytes: 16048
total tree bytes: 1265664
total fs tree bytes: 1118208
total extent tree bytes: 65536
btree space waste bytes: 562598
file data blocks allocated: 65978368
referenced 36569088

Fix this by updating btrfs_block_can_be_shared() to consider that an
extent buffer may be shared if it matches the commit root and if its
generation matches the current transaction's generation.

This can be reproduced with the following script:

$ cat test.sh
#!/bin/bash

MNT=/mnt/sdi
DEV=/dev/sdi

# Use a filesystem with a 64K node size so that we have the same node
# size on every machine regardless of its page size (on x86_64 default
# node size is 16K due to the 4K page size, while on PPC it's 64K by
# default). This way we can make sure we are able to create a btree for
# the subvolume with a height of 2.
mkfs.btrfs -f -n 64K $DEV
mount $DEV $MNT

btrfs subvolume create $MNT/subvol

# Create a few empty files on the subvolume, this bumps its btree
# height to 2 (root node at level 1 and 2 leaves).
for ((i = 1; i <= 300; i++)); do
echo -n > $MNT/subvol/file_$i
done

btrfs subvolume snapshot -r $MNT/subvol $MNT/subvol/snap

umount $DEV

btrfs check $DEV

Running it on a 6.5 kernel (or any 6.6-rc kernel at the moment):

$ ./test.sh
Create subvolume '/mnt/sdi/subvol'
Create a readonly snapshot of '/mnt/sdi/subvol' in '/mnt/sdi/subvol/snap'
Opening filesystem to check...
Checking filesystem on /dev/sdi
UUID: bbdde2ff-7d02-45ca-8a73-3c36f23755a1
[1/7] checking root items
[2/7] checking extents
parent transid verify failed on 30539776 wanted 7 found 5
parent transid verify failed on 30539776 wanted 7 found 5
parent transid verify failed on 30539776 wanted 7 found 5
Ignoring transid failure
owner ref check failed [30539776 65536]
ERROR: errors found in extent allocation tree or chunk allocation
[3/7] checking free space tree
[4/7] checking fs roots
parent transid verify failed on 30539776 wanted 7 found 5
Ignoring transid failure
Wrong key of child node/leaf, wanted: (256, 1, 0), have: (2, 132, 0)
Wrong generation of child node/leaf, wanted: 5, have: 7
root 257 root dir 256 not found
ERROR: errors found in fs roots
found 917504 bytes used, error(s) found
total csum bytes: 0
total tree bytes: 851968
total fs tree bytes: 393216
total extent tree bytes: 65536
btree space waste bytes: 736550
file data blocks allocated: 0
referenced 0

A test case for fstests will follow soon.

Fixes: 1b53e51a4a8f ("btrfs: don't commit transaction for every subvol create")
CC: stable@vger.kernel.org # 6.5+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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btrfs: fix infinite directory reads

The readdir implementation currently processes always up to the last index
it finds. This however can result in an infinite loop if the directory has
a large numb

btrfs: fix infinite directory reads

The readdir implementation currently processes always up to the last index
it finds. This however can result in an infinite loop if the directory has
a large number of entries such that they won't all fit in the given buffer
passed to the readdir callback, that is, dir_emit() returns a non-zero
value. Because in that case readdir() will be called again and if in the
meanwhile new directory entries were added and we still can't put all the
remaining entries in the buffer, we keep repeating this over and over.

The following C program and test script reproduce the problem:

$ cat /mnt/readdir_prog.c
#include <sys/types.h>
#include <dirent.h>
#include <stdio.h>

int main(int argc, char *argv[])
{
DIR *dir = opendir(".");
struct dirent *dd;

while ((dd = readdir(dir))) {
printf("%s\n", dd->d_name);
rename(dd->d_name, "TEMPFILE");
rename("TEMPFILE", dd->d_name);
}
closedir(dir);
}

$ gcc -o /mnt/readdir_prog /mnt/readdir_prog.c

$ cat test.sh
#!/bin/bash

DEV=/dev/sdi
MNT=/mnt/sdi

mkfs.btrfs -f $DEV &> /dev/null
#mkfs.xfs -f $DEV &> /dev/null
#mkfs.ext4 -F $DEV &> /dev/null

mount $DEV $MNT

mkdir $MNT/testdir
for ((i = 1; i <= 2000; i++)); do
echo -n > $MNT/testdir/file_$i
done

cd $MNT/testdir
/mnt/readdir_prog

cd /mnt

umount $MNT

This behaviour is surprising to applications and it's unlike ext4, xfs,
tmpfs, vfat and other filesystems, which always finish. In this case where
new entries were added due to renames, some file names may be reported
more than once, but this varies according to each filesystem - for example
ext4 never reported the same file more than once while xfs reports the
first 13 file names twice.

So change our readdir implementation to track the last index number when
opendir() is called and then make readdir() never process beyond that
index number. This gives the same behaviour as ext4.

Reported-by: Rob Landley <rob@landley.net>
Link: https://lore.kernel.org/linux-btrfs/2c8c55ec-04c6-e0dc-9c5c-8c7924778c35@landley.net/
Link: https://bugzilla.kernel.org/show_bug.cgi?id=217681
CC: stable@vger.kernel.org # 6.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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btrfs: do not BUG_ON() on tree mod log failures at btrfs_del_ptr()

At btrfs_del_ptr(), instead of doing a BUG_ON() in case we fail to record
tree mod log operations, do a transaction abort and retur

btrfs: do not BUG_ON() on tree mod log failures at btrfs_del_ptr()

At btrfs_del_ptr(), instead of doing a BUG_ON() in case we fail to record
tree mod log operations, do a transaction abort and return the error to
the callers. There's really no need for the BUG_ON() as we can release all
resources in the context of all callers, and we have to abort because other
future tree searches that use the tree mod log (btrfs_search_old_slot())
may get inconsistent results if other operations modify the tree after
that failure and before the tree mod log based search.

This implies btrfs_del_ptr() return an int instead of void, and making all
callers check for returned errors.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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btrfs: rename del_ptr to btrfs_del_ptr and export it

This exists internal to ctree.c, however btrfs check needs to use it for
some of its operations. I'd rather not duplicate that code inside of
bt

btrfs: rename del_ptr to btrfs_del_ptr and export it

This exists internal to ctree.c, however btrfs check needs to use it for
some of its operations. I'd rather not duplicate that code inside of
btrfs check as this is low level and I want to keep this code in one
place, so rename the function to btrfs_del_ptr and export it so that it
can be used inside of btrfs-progs safely. Add a comment to make sure
this doesn't get removed by a future cleanup.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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btrfs: add a btrfs_csum_type_size helper

This is needed in btrfs-progs for the tools that convert the checksum
types for file systems and a few other things. We don't have it in the
kernel as we ju

btrfs: add a btrfs_csum_type_size helper

This is needed in btrfs-progs for the tools that convert the checksum
types for file systems and a few other things. We don't have it in the
kernel as we just want to get the size for the super blocks type.
However I don't want to have to manually add this every time we sync
ctree.c into btrfs-progs, so add the helper in the kernel with a note so
it doesn't get removed by a later cleanup.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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btrfs: print-tree: pass const extent buffer pointer

Since print-tree infrastructure only prints the content of a tree block,
we can make them to accept const extent buffer pointer.

This removes a f

btrfs: print-tree: pass const extent buffer pointer

Since print-tree infrastructure only prints the content of a tree block,
we can make them to accept const extent buffer pointer.

This removes a forced type convert in extent-tree, where we convert a
const extent buffer pointer to regular one, just to avoid compiler
warning.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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btrfs: unexport btrfs_prev_leaf()

btrfs_prev_leaf() is not used outside ctree.c, so there's no need to
export it at ctree.h - just make it static at ctree.c and move its
definition above btrfs_searc

btrfs: unexport btrfs_prev_leaf()

btrfs_prev_leaf() is not used outside ctree.c, so there's no need to
export it at ctree.h - just make it static at ctree.c and move its
definition above btrfs_search_slot_for_read(), since that function
calls it.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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btrfs: open code btrfs_bin_search()

btrfs_bin_search() is a simple wrapper that searches for the whole slots
by calling btrfs_generic_bin_search() with the starting slot/first_slot
preset to 0.

Thi

btrfs: open code btrfs_bin_search()

btrfs_bin_search() is a simple wrapper that searches for the whole slots
by calling btrfs_generic_bin_search() with the starting slot/first_slot
preset to 0.

This simple wrapper can be open coded as btrfs_bin_search().

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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btrfs: do unsigned integer division in the extent buffer binary search loop

In the search loop of the binary search function, we are doing a division
by 2 of the sum of the high and low slots. Becau

btrfs: do unsigned integer division in the extent buffer binary search loop

In the search loop of the binary search function, we are doing a division
by 2 of the sum of the high and low slots. Because the slots are integers,
the generated assembly code for it is the following on x86_64:

0x00000000000141f1 <+145>: mov %eax,%ebx
0x00000000000141f3 <+147>: shr $0x1f,%ebx
0x00000000000141f6 <+150>: add %eax,%ebx
0x00000000000141f8 <+152>: sar %ebx

It's a few more instructions than a simple right shift, because signed
integer division needs to round towards zero. However we know that slots
can never be negative (btrfs_header_nritems() returns an u32), so we
can instead use unsigned types for the low and high slots and therefore
use unsigned integer division, which results in a single instruction on
x86_64:

0x00000000000141f0 <+144>: shr %ebx

So use unsigned types for the slots and therefore unsigned division.

This is part of a small patchset comprised of the following two patches:

btrfs: eliminate extra call when doing binary search on extent buffer
btrfs: do unsigned integer division in the extent buffer binary search loop

The following fs_mark test was run on a non-debug kernel (Debian's default
kernel config) before and after applying the patchset:

$ cat test.sh
#!/bin/bash

DEV=/dev/sdi
MNT=/mnt/sdi
MOUNT_OPTIONS="-o ssd"
MKFS_OPTIONS="-O no-holes -R free-space-tree"
FILES=100000
THREADS=$(nproc --all)
FILE_SIZE=0

umount $DEV &> /dev/null
mkfs.btrfs -f $MKFS_OPTIONS $DEV
mount $MOUNT_OPTIONS $DEV $MNT

OPTS="-S 0 -L 6 -n $FILES -s $FILE_SIZE -t $THREADS -k"
for ((i = 1; i <= $THREADS; i++)); do
OPTS="$OPTS -d $MNT/d$i"
done

fs_mark $OPTS

umount $MNT

Results before applying patchset:

FSUse% Count Size Files/sec App Overhead
2 1200000 0 174472.0 11549868
4 2400000 0 253503.0 11694618
4 3600000 0 257833.1 11611508
6 4800000 0 247089.5 11665983
6 6000000 0 211296.1 12121244
10 7200000 0 187330.6 12548565

Results after applying patchset:

FSUse% Count Size Files/sec App Overhead
2 1200000 0 207556.0 11393252
4 2400000 0 266751.1 11347909
4 3600000 0 274397.5 11270058
6 4800000 0 259608.4 11442250
6 6000000 0 238895.8 11635921
8 7200000 0 211942.2 11873825

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: eliminate extra call when doing binary search on extent buffer

The function btrfs_bin_search() is just a wrapper around the function
generic_bin_search(), which passes the same arguments plus

btrfs: eliminate extra call when doing binary search on extent buffer

The function btrfs_bin_search() is just a wrapper around the function
generic_bin_search(), which passes the same arguments plus a default
low slot with a value of 0. This adds an unnecessary extra function
call, since btrfs_bin_search() is not static. So improve on this by
making btrfs_bin_search() an inline function that calls
generic_bin_search(), renaming the later to btrfs_generic_bin_search()
and exporting it.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: move the csum helpers into ctree.h

These got moved because of copy+paste, but this code exists in ctree.c,
so move the declarations back into ctree.h.

Signed-off-by: Josef Bacik <josef@toxic

btrfs: move the csum helpers into ctree.h

These got moved because of copy+paste, but this code exists in ctree.c,
so move the declarations back into ctree.h.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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btrfs: move eb offset helpers into extent_io.h

These are very specific to how the extent buffer is defined, so this
differs between btrfs-progs and the kernel. Make things easier by
moving these he

btrfs: move eb offset helpers into extent_io.h

These are very specific to how the extent buffer is defined, so this
differs between btrfs-progs and the kernel. Make things easier by
moving these helpers into extent_io.h so we don't have to worry about
this when syncing ctree.h.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: move file_extent_item helpers into file-item.h

These helpers use functions that are in multiple places, which makes it
tricky to sync them into btrfs-progs. Move them to file-item.h and then

btrfs: move file_extent_item helpers into file-item.h

These helpers use functions that are in multiple places, which makes it
tricky to sync them into btrfs-progs. Move them to file-item.h and then
include file-item.h in places that use these helpers.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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btrfs: move root helpers back into ctree.h

These accidentally got brought into accessors.h, but belong with the
btrfs_root definitions which are currently in ctree.h. Move these to
make it easier t

btrfs: move root helpers back into ctree.h

These accidentally got brought into accessors.h, but belong with the
btrfs_root definitions which are currently in ctree.h. Move these to
make it easier to sync accessors.[ch] into btrfs-progs.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: use cached state when looking for delalloc ranges with lseek

During lseek (SEEK_HOLE/DATA), whenever we find a hole or prealloc extent,
we will look for delalloc in that range, and one of the

btrfs: use cached state when looking for delalloc ranges with lseek

During lseek (SEEK_HOLE/DATA), whenever we find a hole or prealloc extent,
we will look for delalloc in that range, and one of the things we do for
that is to find out ranges in the inode's io_tree marked with
EXTENT_DELALLOC, using calls to count_range_bits().

Typically there's a single, or few, searches in the io_tree for delalloc
per lseek call. However it's common for applications to keep calling
lseek with SEEK_HOLE and SEEK_DATA to find where extents and holes are in
a file, read the extents and skip holes in order to avoid unnecessary IO
and save disk space by preserving holes.

One popular user is the cp utility from coreutils. Starting with coreutils
9.0, cp uses SEEK_HOLE and SEEK_DATA to iterate over the extents of a
file. Before 9.0, it used fiemap to figure out where holes and extents are
in the source file. Another popular user is the tar utility when used with
the --sparse / -S option to detect and preserve holes.

Given that the pattern is to keep calling lseek with a start offset that
matches the returned offset from the previous lseek call, we can benefit
from caching the last extent state visited in count_range_bits() and use
it for the next count_range_bits() from the next lseek call. Example,
the following strace excerpt from running tar:

$ strace tar cJSvf foo.tar.xz qemu_disk_file.raw
(...)
lseek(5, 125019574272, SEEK_HOLE) = 125024989184
lseek(5, 125024989184, SEEK_DATA) = 125024993280
lseek(5, 125024993280, SEEK_HOLE) = 125025239040
lseek(5, 125025239040, SEEK_DATA) = 125025255424
lseek(5, 125025255424, SEEK_HOLE) = 125025353728
lseek(5, 125025353728, SEEK_DATA) = 125025357824
lseek(5, 125025357824, SEEK_HOLE) = 125026766848
lseek(5, 125026766848, SEEK_DATA) = 125026770944
lseek(5, 125026770944, SEEK_HOLE) = 125027053568
(...)

Shows that pattern, which is the same as with cp from coreutils 9.0+.

So start using a cached state for the delalloc searches in lseek, and
store it in struct file's private data so that it can be reused across
lseek calls.

This change is part of a patchset that is comprised of the following
patches:

1/9 btrfs: remove leftover setting of EXTENT_UPTODATE state in an inode's io_tree
2/9 btrfs: add an early exit when searching for delalloc range for lseek/fiemap
3/9 btrfs: skip unnecessary delalloc searches during lseek/fiemap
4/9 btrfs: search for delalloc more efficiently during lseek/fiemap
5/9 btrfs: remove no longer used btrfs_next_extent_map()
6/9 btrfs: allow passing a cached state record to count_range_bits()
7/9 btrfs: update stale comment for count_range_bits()
8/9 btrfs: use cached state when looking for delalloc ranges with fiemap
9/9 btrfs: use cached state when looking for delalloc ranges with lseek

The following test was run before and after applying the whole patchset:

$ cat test-cp.sh
#!/bin/bash

DEV=/dev/sdh
MNT=/mnt/sdh

# coreutils 8.32, cp uses fiemap to detect holes and extents
#CP_PROG=/usr/bin/cp
# coreutils 9.1, cp uses SEEK_HOLE/DATA to detect holes and extents
CP_PROG=/home/fdmanana/git/hub/coreutils/src/cp

umount $DEV &> /dev/null
mkfs.btrfs -f $DEV
mount $DEV $MNT

FILE_SIZE=$((1024 * 1024 * 1024))
echo "Creating file with a size of $((FILE_SIZE / 1024 / 1024))M"
# Create a very sparse file, where each extent has a length of 4K and
# is preceded by a 4K hole and followed by another 4K hole.
start=$(date +%s%N)
echo -n > $MNT/foobar
for ((off = 0; off < $FILE_SIZE; off += 8192)); do
xfs_io -c "pwrite -S 0xab $off 4K" $MNT/foobar > /dev/null
echo -ne "\r$off / $FILE_SIZE ..."
done
end=$(date +%s%N)
echo -e "\nFile created ($(( (end - start) / 1000000 )) milliseconds)"

start=$(date +%s%N)
$CP_PROG $MNT/foobar /dev/null
end=$(date +%s%N)
dur=$(( (end - start) / 1000000 ))
echo "cp took $dur milliseconds with data/metadata cached and delalloc"

# Flush all delalloc.
sync

start=$(date +%s%N)
$CP_PROG $MNT/foobar /dev/null
end=$(date +%s%N)
dur=$(( (end - start) / 1000000 ))
echo "cp took $dur milliseconds with data/metadata cached and no delalloc"

# Unmount and mount again to test the case without any metadata
# loaded in memory.
umount $MNT
mount $DEV $MNT

start=$(date +%s%N)
$CP_PROG $MNT/foobar /dev/null
end=$(date +%s%N)
dur=$(( (end - start) / 1000000 ))
echo "cp took $dur milliseconds without data/metadata cached and no delalloc"

umount $MNT

The results, running on a box with a non-debug kernel (Debian's default
kernel config), were the following:

128M file, before patchset:

cp took 16574 milliseconds with data/metadata cached and delalloc
cp took 122 milliseconds with data/metadata cached and no delalloc
cp took 20144 milliseconds without data/metadata cached and no delalloc

128M file, after patchset:

cp took 6277 milliseconds with data/metadata cached and delalloc
cp took 109 milliseconds with data/metadata cached and no delalloc
cp took 210 milliseconds without data/metadata cached and no delalloc

512M file, before patchset:

cp took 14369 milliseconds with data/metadata cached and delalloc
cp took 429 milliseconds with data/metadata cached and no delalloc
cp took 88034 milliseconds without data/metadata cached and no delalloc

512M file, after patchset:

cp took 12106 milliseconds with data/metadata cached and delalloc
cp took 427 milliseconds with data/metadata cached and no delalloc
cp took 824 milliseconds without data/metadata cached and no delalloc

1G file, before patchset:

cp took 10074 milliseconds with data/metadata cached and delalloc
cp took 886 milliseconds with data/metadata cached and no delalloc
cp took 181261 milliseconds without data/metadata cached and no delalloc

1G file, after patchset:

cp took 3320 milliseconds with data/metadata cached and delalloc
cp took 880 milliseconds with data/metadata cached and no delalloc
cp took 1801 milliseconds without data/metadata cached and no delalloc

Reported-by: Wang Yugui <wangyugui@e16-tech.com>
Link: https://lore.kernel.org/linux-btrfs/20221106073028.71F9.409509F4@e16-tech.com/
Link: https://lore.kernel.org/linux-btrfs/CAL3q7H5NSVicm7nYBJ7x8fFkDpno8z3PYt5aPU43Bajc1H0h1Q@mail.gmail.com/
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: move orphan prototypes into orphan.h

Move these out of ctree.h into orphan.h to cut down on code in ctree.h.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dste

btrfs: move orphan prototypes into orphan.h

Move these out of ctree.h into orphan.h to cut down on code in ctree.h.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: move super prototypes into super.h

Move these out of ctree.h into super.h to cut down on code in ctree.h.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Ba

btrfs: move super prototypes into super.h

Move these out of ctree.h into super.h to cut down on code in ctree.h.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: move CONFIG_BTRFS_FS_RUN_SANITY_TESTS checks to fs.h

We already have a few of these in fs.h, move the remaining checks out of
ctree.h into fs.h.

Reviewed-by: Johannes Thumshirn <johannes.thu

btrfs: move CONFIG_BTRFS_FS_RUN_SANITY_TESTS checks to fs.h

We already have a few of these in fs.h, move the remaining checks out of
ctree.h into fs.h.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: move verity prototypes into verity.h

Move these out of ctree.h into verity.h to cut down on code in ctree.h.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef

btrfs: move verity prototypes into verity.h

Move these out of ctree.h into verity.h to cut down on code in ctree.h.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: move dev-replace prototypes into dev-replace.h

We already have a dev-replace.h, simply move these prototypes and
helpers into dev-replace.h where they belong.

Reviewed-by: Johannes Thumshirn

btrfs: move dev-replace prototypes into dev-replace.h

We already have a dev-replace.h, simply move these prototypes and
helpers into dev-replace.h where they belong.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: move scrub prototypes into scrub.h

Move these out of ctree.h into scrub.h to cut down on code in ctree.h.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Ba

btrfs: move scrub prototypes into scrub.h

Move these out of ctree.h into scrub.h to cut down on code in ctree.h.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: move relocation prototypes into relocation.h

Move these out of ctree.h into relocation.h to cut down on code in
ctree.h

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-of

btrfs: move relocation prototypes into relocation.h

Move these out of ctree.h into relocation.h to cut down on code in
ctree.h

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: move acl prototypes into acl.h

Move these out of ctree.h into acl.h to cut down on code in ctree.h.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <j

btrfs: move acl prototypes into acl.h

Move these out of ctree.h into acl.h to cut down on code in ctree.h.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: move the snapshot drop related prototypes to extent-tree.h

These belong in extent-tree.h, they were missed because they were not
grouped with the other extent-tree.c prototypes.

Reviewed-by:

btrfs: move the snapshot drop related prototypes to extent-tree.h

These belong in extent-tree.h, they were missed because they were not
grouped with the other extent-tree.c prototypes.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...