A comment at log_conflicting_inodes() mentions that we check the inode's
logged_trans field instead of using btrfs_inode_in_log() because the field
last_log_commit is not updated when we log that an inode exists and the
inode has the full sync flag (BTRFS_INODE_NEEDS_FULL_SYNC) set. The part
about the full sync flag is not true anymore since commit 9acc8103ab
("btrfs: fix unpersisted i_size on fsync after expanding truncate"), so
update the comment to not mention that part anymore.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Now that we are checking if the inode's logged_trans is 0 to detect the
possibility of the inode having been evicted and reloaded, the test for
the full sync flag (BTRFS_INODE_NEEDS_FULL_SYNC) is no longer needed at
tree-log.c:inode_logged(). Its purpose was to detect the possibility
of a previous eviction as well, since when an inode is loaded the full
sync flag is always set on it (and only cleared after the inode is
logged).
So just remove the check and update the comment. The check for the inode's
logged_trans being 0 was added recently by the patch with the subject
"btrfs: eliminate some false positives when checking if inode was logged".
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
At the very end of btrfs_rename_exchange(), in case an error happened, we
are checking if 'new_inode' is NULL, but that is not needed since during a
rename exchange, unlike regular renames, 'new_inode' can never be NULL,
and if it were, we would have a crashed much earlier when we dereference it
multiple times.
So remove the check because it is not necessary and because it is causing
static checkers to emit a warning. I probably introduced the check by
copy-pasting similar code from btrfs_rename(), where 'new_inode' can be
NULL, in commit 86e8aa0e77 ("Btrfs: unpin logs if rename exchange
operation fails").
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.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 using kmalloc() to allocate backref_ctx, allocate backref_ctx
on stack. The size is reasonably small.
sizeof(backref_ctx) = 48
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Instead of using kmalloc() to allocate btrfs_ioctl_defrag_range_args,
allocate btrfs_ioctl_defrag_range_args on stack, the size is reasonably
small and ioctls are called in process context.
sizeof(btrfs_ioctl_defrag_range_args) = 48
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Instead of using kmalloc() to allocate btrfs_ioctl_quota_rescan_args,
allocate btrfs_ioctl_quota_rescan_args on stack, the size is reasonably
small and ioctls are called in process context.
sizeof(btrfs_ioctl_quota_rescan_args) = 64
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
It's a common practice to start a search using offset (u64)-1, which is
the u64 maximum value, meaning that we want the search_slot function to
be set in the last item with the same objectid and type.
Once we are in this position, it's a matter to start a search backwards
by calling btrfs_previous_item, which will check if we'll need to go to
a previous leaf and other necessary checks, only to be sure that we are
in last offset of the same object and type.
The new btrfs_search_backwards function does the all these steps when
necessary, and can be used to avoid code duplication.
Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
As fsverity support depends on a config option, print that at module
load time like we do for similar features.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Writing out the verity data is too large of an operation to do in a
single transaction. If we are interrupted before we finish creating
fsverity metadata for a file, or fail to clean up already created
metadata after a failure, we could leak the verity items that we already
committed.
To address this issue, we use the orphan mechanism. When we start
enabling verity on a file, we also add an orphan item for that inode.
When we are finished, we delete the orphan. However, if we are
interrupted midway, the orphan will be present at mount and we can
cleanup the half-formed verity state.
There is a possible race with a normal unlink operation: if unlink and
verity run on the same file in parallel, it is possible for verity to
succeed and delete the still legitimate orphan added by unlink. Then, if
we are interrupted and mount in that state, we will never clean up the
inode properly. This is also possible for a file created with O_TMPFILE.
Check nlink==0 before deleting to avoid this race.
A final thing to note is that this is a resurrection of using orphans to
signal an operation besides "delete this inode". The old case was to
signal the need to do a truncate. That case still technically applies
for mounting very old file systems, so we need to take some care to not
clobber it. To that end, we just have to be careful that verity orphan
cleanup is a no-op for non-verity files.
Signed-off-by: Boris Burkov <boris@bur.io>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Add support for fsverity in btrfs. To support the generic interface in
fs/verity, we add two new item types in the fs tree for inodes with
verity enabled. One stores the per-file verity descriptor and btrfs
verity item and the other stores the Merkle tree data itself.
Verity checking is done in end_page_read just before a page is marked
uptodate. This naturally handles a variety of edge cases like holes,
preallocated extents, and inline extents. Some care needs to be taken to
not try to verity pages past the end of the file, which are accessed by
the generic buffered file reading code under some circumstances like
reading to the end of the last page and trying to read again. Direct IO
on a verity file falls back to buffered reads.
Verity relies on PageChecked for the Merkle tree data itself to avoid
re-walking up shared paths in the tree. For this reason, we need to
cache the Merkle tree data. Since the file is immutable after verity is
turned on, we can cache it at an index past EOF.
Use the new inode ro_flags to store verity on the inode item, so that we
can enable verity on a file, then rollback to an older kernel and still
mount the file system and read the file. Since we can't safely write the
file anymore without ruining the invariants of the Merkle tree, we mark
a ro_compat flag on the file system when a file has verity enabled.
Acked-by: Eric Biggers <ebiggers@google.com>
Co-developed-by: Chris Mason <clm@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently, inode flags are fully backwards incompatible in btrfs. If we
introduce a new inode flag, then tree-checker will detect it and fail.
This can even cause us to fail to mount entirely. To make it possible to
introduce new flags which can be read-only compatible, like VERITY, we
add new ro flags to btrfs without treating them quite so harshly in
tree-checker. A read-only file system can survive an unexpected flag,
and can be mounted.
As for the implementation, it unfortunately gets a little complicated.
The on-disk representation of the inode, btrfs_inode_item, has an __le64
for flags but the in-memory representation, btrfs_inode, uses a u32.
David Sterba had the nice idea that we could reclaim those wasted 32 bits
on disk and use them for the new ro_compat flags.
It turns out that the tree-checker code which checks for unknown flags
is broken, and ignores the upper 32 bits we are hoping to use. The issue
is that the flags use the literal 1 rather than 1ULL, so the flags are
signed ints, and one of them is specifically (1 << 31). As a result, the
mask which ORs the flags is a negative integer on machines where int is
32 bit twos complement. When tree-checker evaluates the expression:
btrfs_inode_flags(leaf, iitem) & ~BTRFS_INODE_FLAG_MASK)
The mask is something like 0x80000abc, which gets promoted to u64 with
sign extension to 0xffffffff80000abc. Negating that 64 bit mask leaves
all the upper bits zeroed, and we can't detect unexpected flags.
This suggests that we can't use those bits after all. Luckily, we have
good reason to believe that they are zero anyway. Inode flags are
metadata, which is always checksummed, so any bit flips that would
introduce 1s would cause a checksum failure anyway (excluding the
improbable case of the checksum getting corrupted exactly badly).
Further, unless the 1 << 31 flag is used, the cast to u64 of the 32 bit
inode flag should preserve its value and not add leading zeroes
(at least for twos complement). The only place that flag
(BTRFS_INODE_ROOT_ITEM_INIT) is used is in a special inode embedded in
the root item, and indeed for that inode we see 0xffffffff80000000 as
the flags on disk. However, that inode is never seen by tree checker,
nor is it used in a context where verity might be meaningful.
Theoretically, a future ro flag might cause trouble on that inode, so we
should proactively clean up that mess before it does.
With the introduction of the new ro flags, keep two separate unsigned
masks and check them against the appropriate u32. Since we no longer run
afoul of sign extension, this also stops writing out 0xffffffff80000000
in root_item inodes going forward.
Signed-off-by: Boris Burkov <boris@bur.io>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Function btrfs_check_raid_min_devices() returns error code from the enum
btrfs_err_code and it starts from 1. So there is no need to check if ret
is > 0. So drop this check and also drop the local variable ret.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When btrfs_run_delalloc_range() failed, we will error out.
But there is a strange comment mentioning that
btrfs_run_delalloc_range() could have returned value >0 to indicate the
IO has already started.
Commit 40f765805f ("Btrfs: split up __extent_writepage to lower stack
usage") introduced the comment, but unfortunately at that time, we were
already using @page_started to indicate that case, and still return 0.
Furthermore, even if that comment was right (which is not), we would
return -EIO if the IO had already started.
By all means the comment is incorrect, just remove the comment along
with the dead check.
Just to be extra safe, add an ASSERT() in btrfs_run_delalloc_range() to
make sure we either return 0 or error, no positive return value.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The data on raid0 and raid10 are supposed to be spread over multiple
devices, so the minimum constraints are set to 2 and 4 respectively.
This is an artificial limit and there's some interest to remove it.
Change this to allow raid0 on one device and raid10 on two devices. This
works as expected eg. when converting or removing devices.
The only difference is when raid0 on two devices gets one device
removed. Unpatched would silently create a single profile, while newly
it would be raid0.
The motivation is to allow to preserve the profile type as long as it
possible for some intermediate state (device removal, conversion), or
when there are disks of different size, with raid0 the otherwise
unusable space of the last device will be used too. Similarly for
raid10, though the two largest devices would need to be the same.
Unpatched kernel will mount and use the degenerate profiles just fine
but won't allow any operation that would not satisfy the stricter device
number constraints, eg. not allowing to go from 3 to 2 devices for
raid10 or various profile conversions.
Example output:
# btrfs fi us -T .
Overall:
Device size: 10.00GiB
Device allocated: 1.01GiB
Device unallocated: 8.99GiB
Device missing: 0.00B
Used: 200.61MiB
Free (estimated): 9.79GiB (min: 9.79GiB)
Free (statfs, df): 9.79GiB
Data ratio: 1.00
Metadata ratio: 1.00
Global reserve: 3.25MiB (used: 0.00B)
Multiple profiles: no
Data Metadata System
Id Path RAID0 single single Unallocated
-- ---------- --------- --------- -------- -----------
1 /dev/sda10 1.00GiB 8.00MiB 1.00MiB 8.99GiB
-- ---------- --------- --------- -------- -----------
Total 1.00GiB 8.00MiB 1.00MiB 8.99GiB
Used 200.25MiB 352.00KiB 16.00KiB
# btrfs dev us .
/dev/sda10, ID: 1
Device size: 10.00GiB
Device slack: 0.00B
Data,RAID0/1: 1.00GiB
Metadata,single: 8.00MiB
System,single: 1.00MiB
Unallocated: 8.99GiB
Note "Data,RAID0/1", with btrfs-progs 5.13+ the number of devices per
profile is printed.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
During renames we pin the logs of the roots a bit too early, before the
calls to btrfs_insert_inode_ref(). We can pin the logs after those calls,
since those will not change anything in a log tree.
In a scenario where we have multiple and diverse filesystem operations
running in parallel, those calls can take a significant amount of time,
due to lock contention on extent buffers, and delay log commits from other
tasks for longer than necessary.
So just pin logs after calls to btrfs_insert_inode_ref() and right before
the first operation that can update a log tree.
The following script that uses dbench was used for testing:
$ cat dbench-test.sh
#!/bin/bash
DEV=/dev/nvme0n1
MNT=/mnt/nvme0n1
MOUNT_OPTIONS="-o ssd"
MKFS_OPTIONS="-m single -d single"
echo "performance" | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
umount $DEV &> /dev/null
mkfs.btrfs -f $MKFS_OPTIONS $DEV
mount $MOUNT_OPTIONS $DEV $MNT
dbench -D $MNT -t 120 16
umount $MNT
The tests were run on a machine with 12 cores, 64G of RAN, a NVMe device
and using a non-debug kernel config (Debian's default config).
The results compare a branch without this patch and without the previous
patch in the series, that has the subject:
"btrfs: eliminate some false positives when checking if inode was logged"
Versus the same branch with these two patches applied.
dbench with 8 clients, results before:
Operation Count AvgLat MaxLat
----------------------------------------
NTCreateX 4391359 0.009 249.745
Close 3225882 0.001 3.243
Rename 185953 0.065 240.643
Unlink 886669 0.049 249.906
Deltree 112 2.455 217.433
Mkdir 56 0.002 0.004
Qpathinfo 3980281 0.004 3.109
Qfileinfo 697579 0.001 0.187
Qfsinfo 729780 0.002 2.424
Sfileinfo 357764 0.004 1.415
Find 1538861 0.016 4.863
WriteX 2189666 0.010 3.327
ReadX 6883443 0.002 0.729
LockX 14298 0.002 0.073
UnlockX 14298 0.001 0.042
Flush 307777 2.447 303.663
Throughput 1149.6 MB/sec 8 clients 8 procs max_latency=303.666 ms
dbench with 8 clients, results after:
Operation Count AvgLat MaxLat
----------------------------------------
NTCreateX 4269920 0.009 213.532
Close 3136653 0.001 0.690
Rename 180805 0.082 213.858
Unlink 862189 0.050 172.893
Deltree 112 2.998 218.328
Mkdir 56 0.002 0.003
Qpathinfo 3870158 0.004 5.072
Qfileinfo 678375 0.001 0.194
Qfsinfo 709604 0.002 0.485
Sfileinfo 347850 0.004 1.304
Find 1496310 0.017 5.504
WriteX 2129613 0.010 2.882
ReadX 6693066 0.002 1.517
LockX 13902 0.002 0.075
UnlockX 13902 0.001 0.055
Flush 299276 2.511 220.189
Throughput 1187.33 MB/sec 8 clients 8 procs max_latency=220.194 ms
+3.2% throughput, -31.8% max latency
dbench with 16 clients, results before:
Operation Count AvgLat MaxLat
----------------------------------------
NTCreateX 5978334 0.028 156.507
Close 4391598 0.001 1.345
Rename 253136 0.241 155.057
Unlink 1207220 0.182 257.344
Deltree 160 6.123 36.277
Mkdir 80 0.003 0.005
Qpathinfo 5418817 0.012 6.867
Qfileinfo 949929 0.001 0.941
Qfsinfo 993560 0.002 1.386
Sfileinfo 486904 0.004 2.829
Find 2095088 0.059 8.164
WriteX 2982319 0.017 9.029
ReadX 9371484 0.002 4.052
LockX 19470 0.002 0.461
UnlockX 19470 0.001 0.990
Flush 418936 2.740 347.902
Throughput 1495.31 MB/sec 16 clients 16 procs max_latency=347.909 ms
dbench with 16 clients, results after:
Operation Count AvgLat MaxLat
----------------------------------------
NTCreateX 5711833 0.029 131.240
Close 4195897 0.001 1.732
Rename 241849 0.204 147.831
Unlink 1153341 0.184 231.322
Deltree 160 6.086 30.198
Mkdir 80 0.003 0.021
Qpathinfo 5177011 0.012 7.150
Qfileinfo 907768 0.001 0.793
Qfsinfo 949205 0.002 1.431
Sfileinfo 465317 0.004 2.454
Find 2001541 0.058 7.819
WriteX 2850661 0.017 9.110
ReadX 8952289 0.002 3.991
LockX 18596 0.002 0.655
UnlockX 18596 0.001 0.179
Flush 400342 2.879 293.607
Throughput 1565.73 MB/sec 16 clients 16 procs max_latency=293.611 ms
+4.6% throughput, -16.9% max latency
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When checking if an inode was previously logged in the current transaction
through the helper inode_logged(), we can return some false positives that
can be easily eliminated. These correspond to the cases where an inode has
a ->logged_trans value that is not zero and its value is smaller then the
ID of the current transaction. This means we know exactly that the inode
was never logged before in the current transaction, so we can return false
and avoid the callers to do extra work:
1) Having btrfs_del_dir_entries_in_log() and btrfs_del_inode_ref_in_log()
unnecessarily join a log transaction and do deletion searches in a log
tree that will not find anything. This just adds unnecessary contention
on extent buffer locks;
2) Having btrfs_log_new_name() unnecessarily log an inode when it is not
needed. If the inode was not logged before, we don't need to log it in
LOG_INODE_EXISTS mode.
So just make sure that any false positive only happens when ->logged_trans
has a value of 0.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When on SINGLE block group, btrfs_get_io_geometry() will return "the
size of the block group - the offset of the logical address within the
block group" as geom.len. Since we allow up to 8 GiB zone size on zoned
filesystem, we can have up to 8 GiB block group, so can have up to 8 GiB
geom.len as well. With this setup, we easily hit the "ASSERT(geom.len <=
INT_MAX);".
The ASSERT looks like to guard btrfs_bio_clone_partial() and bio_trim()
which both take "int" (now u64 due to the previous patch). So to be
precise the ASSERT should check if clone_len <= UINT_MAX. But actually,
clone_len is already capped by bio.bi_iter.bi_size which is unsigned
int. So the ASSERT is not necessary.
Drop the ASSERT and properly compare submit_len and geom.len in u64.
Then, let the implicit casting to convert it to u64.
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The offset and can never be negative use unsigned int instead of int
type for them.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The function bio_trim has offset and size arguments that are declared
as int.
The callers of this function use sector_t type when passing the offset
and size, e.g. drivers/md/raid1.c:narrow_write_error() and
drivers/md/raid1.c:narrow_write_error().
Change offset and size arguments to sector_t type for bio_trim(). Also,
add WARN_ON_ONCE() to catch their overflow.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Now that all users of sync_inode() have been deleted, remove
sync_inode().
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We're going to remove sync_inode, so migrate to filemap_fdatawrite_wbc
instead.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
sync_inode() has some holes that can cause problems if we're under heavy
ENOSPC pressure. If there's writeback running on a separate thread
sync_inode() will skip writing the inode altogether. What we really
want is to make sure writeback has been started on all the pages to make
sure we can see the ordered extents and wait on them if appropriate.
Switch to this new helper which will allow us to accomplish this and
avoid ENOSPC'ing early.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Btrfs sometimes needs to flush dirty pages on a bunch of dirty inodes in
order to reclaim metadata reservations. Unfortunately most helpers in
this area are too smart for us:
1) The normal filemap_fdata* helpers only take range and sync modes, and
don't give any indication of how much was written, so we can only
flush full inodes, which isn't what we want in most cases.
2) The normal writeback path requires us to have the s_umount sem held,
but we can't unconditionally take it in this path because we could
deadlock.
3) The normal writeback path also skips inodes with I_SYNC set if we
write with WB_SYNC_NONE. This isn't the behavior we want under heavy
ENOSPC pressure, we want to actually make sure the pages are under
writeback before returning, and if another thread is in the middle of
writing the file we may return before they're under writeback and
miss our ordered extents and not properly wait for completion.
4) sync_inode() uses the normal writeback path and has the same problem
as #3.
What we really want is to call do_writepages() with our wbc. This way
we can make sure that writeback is actually started on the pages, and we
can control how many pages are written as a whole as we write many
inodes using the same wbc. Accomplish this with a new helper that does
just that so we can use it for our ENOSPC flushing infrastructure.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
I've been debugging an early ENOSPC problem in production and finally
root caused it to this problem. When we switched to the per-inode in
38d715f494 ("btrfs: use btrfs_start_delalloc_roots in
shrink_delalloc") I pulled out the async extent handling, because we
were doing the correct thing by calling filemap_flush() if we had async
extents set. This would properly wait on any async extents by locking
the page in the second flush, thus making sure our ordered extents were
properly set up.
However when I switched us back to page based flushing, I used
sync_inode(), which allows us to pass in our own wbc. The problem here
is that sync_inode() is smarter than the filemap_* helpers, it tries to
avoid calling writepages at all. This means that our second call could
skip calling do_writepages altogether, and thus not wait on the pagelock
for the async helpers. This means we could come back before any ordered
extents were created and then simply continue on in our flushing
mechanisms and ENOSPC out when we have plenty of space to use.
Fix this by putting back the async pages logic in shrink_delalloc. This
allows us to bulk write out everything that we need to, and then we can
wait in one place for the async helpers to catch up, and then wait on
any ordered extents that are created.
Fixes: e076ab2a2c ("btrfs: shrink delalloc pages instead of full inodes")
CC: stable@vger.kernel.org # 5.10+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We have been hitting some early ENOSPC issues in production with more
recent kernels, and I tracked it down to us simply not flushing delalloc
as aggressively as we should be. With tracing I was seeing us failing
all tickets with all of the block rsvs at or around 0, with very little
pinned space, but still around 120MiB of outstanding bytes_may_used.
Upon further investigation I saw that we were flushing around 14 pages
per shrink call for delalloc, despite having around 2GiB of delalloc
outstanding.
Consider the example of a 8 way machine, all CPUs trying to create a
file in parallel, which at the time of this commit requires 5 items to
do. Assuming a 16k leaf size, we have 10MiB of total metadata reclaim
size waiting on reservations. Now assume we have 128MiB of delalloc
outstanding. With our current math we would set items to 20, and then
set to_reclaim to 20 * 256k, or 5MiB.
Assuming that we went through this loop all 3 times, for both
FLUSH_DELALLOC and FLUSH_DELALLOC_WAIT, and then did the full loop
twice, we'd only flush 60MiB of the 128MiB delalloc space. This could
leave a fair bit of delalloc reservations still hanging around by the
time we go to ENOSPC out all the remaining tickets.
Fix this two ways. First, change the calculations to be a fraction of
the total delalloc bytes on the system. Prior to this change we were
calculating based on dirty inodes so our math made more sense, now it's
just completely unrelated to what we're actually doing.
Second add a FLUSH_DELALLOC_FULL state, that we hold off until we've
gone through the flush states at least once. This will empty the system
of all delalloc so we're sure to be truly out of space when we start
failing tickets.
I'm tagging stable 5.10 and forward, because this is where we started
using the page stuff heavily again. This affects earlier kernel
versions as well, but would be a pain to backport to them as the
flushing mechanisms aren't the same.
CC: stable@vger.kernel.org # 5.10+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When debugging early enospc problems it was useful to have a tracepoint
where we failed all tickets so I could check the state of the enospc
counters at failure time to validate my fixes. This adds the tracpoint
so you can easily get that information.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In order to debug delalloc flushing issues I added delalloc_bytes and
ordered_bytes to this tracepoint to see if they were non-zero when we
were going ENOSPC. This was valuable for me and showed me cases where we
weren't waiting on ordered extents properly. In order to add this to the
tracepoint we need to take away the const modifier for fs_info, as
percpu_sum_counter_positive() will change the counter when it adds up
the percpu buckets. This is needed to make sure we're getting accurate
information at these tracepoints, as the wrong information could send us
down the wrong path when debugging problems.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We use the async_delalloc_pages mechanism to make sure that we've
completed our async work before trying to continue our delalloc
flushing. The reason for this is we need to see any ordered extents
that were created by our delalloc flushing. However we're waking up
before we do the submit work, which is before we create the ordered
extents. This is a pretty wide race window where we could potentially
think there are no ordered extents and thus exit shrink_delalloc
prematurely. Fix this by waking us up after we've done the work to
create ordered extents.
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
When running btrfs/160 in a loop for subpage with experimental
compression support, it has a high chance to crash (~20%):
BTRFS critical (device dm-7): panic in __btrfs_add_ordered_extent:238: inconsistency in ordered tree at offset 0 (errno=-17 Object already exists)
------------[ cut here ]------------
kernel BUG at fs/btrfs/ordered-data.c:238!
Internal error: Oops - BUG: 0 [#1] SMP
pc : __btrfs_add_ordered_extent+0x550/0x670 [btrfs]
lr : __btrfs_add_ordered_extent+0x550/0x670 [btrfs]
Call trace:
__btrfs_add_ordered_extent+0x550/0x670 [btrfs]
btrfs_add_ordered_extent+0x2c/0x50 [btrfs]
run_delalloc_nocow+0x81c/0x8fc [btrfs]
btrfs_run_delalloc_range+0xa4/0x390 [btrfs]
writepage_delalloc+0xc0/0x1ac [btrfs]
__extent_writepage+0xf4/0x370 [btrfs]
extent_write_cache_pages+0x288/0x4f4 [btrfs]
extent_writepages+0x58/0xe0 [btrfs]
btrfs_writepages+0x1c/0x30 [btrfs]
do_writepages+0x60/0x110
__filemap_fdatawrite_range+0x108/0x170
filemap_fdatawrite_range+0x20/0x30
btrfs_fdatawrite_range+0x34/0x4dc [btrfs]
__btrfs_write_out_cache+0x34c/0x480 [btrfs]
btrfs_write_out_cache+0x144/0x220 [btrfs]
btrfs_start_dirty_block_groups+0x3ac/0x6b0 [btrfs]
btrfs_commit_transaction+0xd0/0xbb4 [btrfs]
btrfs_sync_fs+0x64/0x1cc [btrfs]
sync_fs_one_sb+0x3c/0x50
iterate_supers+0xcc/0x1d4
ksys_sync+0x6c/0xd0
__arm64_sys_sync+0x1c/0x30
invoke_syscall+0x50/0x120
el0_svc_common.constprop.0+0x4c/0xd4
do_el0_svc+0x30/0x9c
el0_svc+0x2c/0x54
el0_sync_handler+0x1a8/0x1b0
el0_sync+0x198/0x1c0
---[ end trace 336f67369ae6e0af ]---
[CAUSE]
For subpage case, we can have multiple sectors inside a page, this makes
it possible for __extent_writepage() to have part of its page submitted
before returning.
In btrfs/160, we are using dm-dust to emulate write error, this means
for certain pages, we could have everything running fine, but at the end
of __extent_writepage(), one of the submitted bios fails due to dm-dust.
Then the page is marked Error, and we change @ret from 0 to -EIO.
This makes the caller extent_write_cache_pages() to error out, without
submitting the remaining pages.
Furthermore, since we're erroring out for free space cache, it doesn't
really care about the error and will update the inode and retry the
writeback.
Then we re-run the delalloc range, and will try to insert the same
delalloc range while previous delalloc range is still hanging there,
triggering the above error.
[FIX]
The proper fix is to handle errors from __extent_writepage() properly,
by ending the remaining ordered extent.
But that fix needs the following changes:
- Know at exactly which sector the error happened
Currently __extent_writepage_io() works for the full page, can't
return at which sector we hit the error.
- Grab the ordered extent covering the failed sector
As a hotfix for subpage case, here we unify the error paths in
__extent_writepage().
In fact, the "if (PageError(page))" branch never get executed if @ret is
still 0 for non-subpage cases.
As for non-subpage case, we never submit current page in
__extent_writepage(), but only add current page into bio.
The bio can only get submitted in next page.
Thus we never get PageError() set due to IO failure, thus when we hit
the branch, @ret is never 0.
By simply removing that @ret assignment, we let subpage case ignore the
IO failure, thus only error out for fatal errors just like regular
sectorsize.
So that IO error won't be treated as fatal error not trigger the hanging
OE problem.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Since now we support data and metadata read-write for subpage, remove
the RO requirement for subpage mount.
There are some extra limitations though:
- For now, subpage RW mount is still considered experimental
Thus that mount warning will still be there.
- No compression support
There are still quite some PAGE_SIZE hard coded and quite some call
sites use extent_clear_unlock_delalloc() to unlock locked_page.
This will screw up subpage helpers.
Now for subpage RW mount, no matter what mount option or inode attr is
set, all writes will not be compressed. Although reading compressed
data has no problem.
- No defrag for subpage case
The defrag support for subpage case will come in later patches, which
will also rework the defrag workflow.
- No inline extent will be created
This is mostly due to the fact that filemap_fdatawrite_range() will
trigger more write than the range specified.
In fallocate calls, this behavior can make us to writeback which can
be inlined, before we enlarge the i_size.
This is a very special corner case, and even current btrfs check won't
report error on such inline extent + regular extent.
But considering how much effort has been put to prevent such inline +
regular, I'd prefer to cut off inline extent completely until we have
a good solution.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
When using the following script, btrfs will report data corruption after
one data balance with subpage support:
mkfs.btrfs -f -s 4k $dev
mount $dev -o nospace_cache $mnt
$fsstress -w -n 8 -s 1620948986 -d $mnt/ -v > /tmp/fsstress
sync
btrfs balance start -d $mnt
btrfs scrub start -B $mnt
Similar problem can be easily observed in btrfs/028 test case, there
will be tons of balance failure with -EIO.
[CAUSE]
Above fsstress will result the following data extents layout in extent
tree:
item 10 key (13631488 EXTENT_ITEM 98304) itemoff 15889 itemsize 82
refs 2 gen 7 flags DATA
extent data backref root FS_TREE objectid 259 offset 1339392 count 1
extent data backref root FS_TREE objectid 259 offset 647168 count 1
item 11 key (13631488 BLOCK_GROUP_ITEM 8388608) itemoff 15865 itemsize 24
block group used 102400 chunk_objectid 256 flags DATA
item 12 key (13733888 EXTENT_ITEM 4096) itemoff 15812 itemsize 53
refs 1 gen 7 flags DATA
extent data backref root FS_TREE objectid 259 offset 729088 count 1
Then when creating the data reloc inode, the data reloc inode will look
like this:
0 32K 64K 96K 100K 104K
|<------ Extent A ----->| |<- Ext B ->|
Then when we first try to relocate extent A, we setup the data reloc
inode with i_size 96K, then read both page [0, 64K) and page [64K, 128K).
For page 64K, since the i_size is just 96K, we fill range [96K, 128K)
with 0 and set it uptodate.
Then when we come to extent B, we update i_size to 104K, then try to read
page [64K, 128K).
Then we find the page is already uptodate, so we skip the read.
But range [96K, 128K) is filled with 0, not the real data.
Then we writeback the data reloc inode to disk, with 0 filling range
[96K, 128K), corrupting the content of extent B.
The behavior is caused by the fact that we still do full page read for
subpage case.
The bug won't really happen for regular sectorsize, as one page only
contains one sector.
[FIX]
This patch will fix the problem by invalidating range [i_size, PAGE_END]
in prealloc_file_extent_cluster().
So that if above example happens, when we preallocate the file extent
for extent B, we will clear the uptodate bits for range [96K, 128K),
allowing later relocate_one_page() to re-read the needed range.
There is a special note for the invalidating part.
Since we're not calling real btrfs_invalidatepage(), but just clearing
the subpage and page uptodate bits, we can leave a page half dirty and
half out of date.
Reading such page can cause a deadlock, as we normally expect a dirty
page to be fully uptodate.
Thus here we flush and wait the data reloc inode before doing the hacked
invalidating. This won't cause extra overhead, as we're going to
writeback the data later anyway.
Reported-by: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
When relocating partial preallocated data extents (part of the
preallocated extent is written) for subpage, it can cause the following
false alert and make the relocation to fail:
BTRFS info (device dm-3): balance: start -d
BTRFS info (device dm-3): relocating block group 13631488 flags data
BTRFS warning (device dm-3): csum failed root -9 ino 257 off 4096 csum 0x98757625 expected csum 0x00000000 mirror 1
BTRFS error (device dm-3): bdev /dev/mapper/arm_nvme-test errs: wr 0, rd 0, flush 0, corrupt 1, gen 0
BTRFS warning (device dm-3): csum failed root -9 ino 257 off 4096 csum 0x98757625 expected csum 0x00000000 mirror 1
BTRFS error (device dm-3): bdev /dev/mapper/arm_nvme-test errs: wr 0, rd 0, flush 0, corrupt 2, gen 0
BTRFS info (device dm-3): balance: ended with status: -5
The minimal script to reproduce looks like this:
mkfs.btrfs -f -s 4k $dev
mount $dev -o nospace_cache $mnt
xfs_io -f -c "falloc 0 8k" $mnt/file
xfs_io -f -c "pwrite 0 4k" $mnt/file
btrfs balance start -d $mnt
[CAUSE]
Function btrfs_verify_data_csum() checks if the full range has
EXTENT_NODATASUM bit for data reloc inode, if *all* bytes of the range
have EXTENT_NODATASUM bit, then it skip the range.
This works pretty well for regular sectorsize, as in that case
btrfs_verify_data_csum() is called for each sector, thus no problem at
all.
But for subpage case, btrfs_verify_data_csum() is called on each bvec,
which can contain several sectors, and since it checks *all* bytes for
EXTENT_NODATASUM bit, if we have some range with csum, then we will
continue checking all the sectors.
For the preallocated sectors, it doesn't have any csum, thus obviously
the csum won't match and cause the false alert.
[FIX]
Move the EXTENT_NODATASUM check into the main loop, so that we can check
each sector for EXTENT_NODATASUM bit for subpage case.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
There is a possible use-after-free bug when running generic/095.
BUG: Unable to handle kernel data access on write at 0x6b6b6b6b6b6b725b
Faulting instruction address: 0xc000000000283654
c000000000283078 do_raw_spin_unlock+0x88/0x230
c0000000012b1e14 _raw_spin_unlock_irqrestore+0x44/0x90
c000000000a918dc btrfs_subpage_clear_writeback+0xac/0xe0
c0000000009e0458 end_bio_extent_writepage+0x158/0x270
c000000000b6fd14 bio_endio+0x254/0x270
c0000000009fc0f0 btrfs_end_bio+0x1a0/0x200
c000000000b6fd14 bio_endio+0x254/0x270
c000000000b781fc blk_update_request+0x46c/0x670
c000000000b8b394 blk_mq_end_request+0x34/0x1d0
c000000000d82d1c lo_complete_rq+0x11c/0x140
c000000000b880a4 blk_complete_reqs+0x84/0xb0
c0000000012b2ca4 __do_softirq+0x334/0x680
c0000000001dd878 irq_exit+0x148/0x1d0
c000000000016f4c do_IRQ+0x20c/0x240
c000000000009240 hardware_interrupt_common_virt+0x1b0/0x1c0
[CAUSE]
There is very small race window like the following in generic/095.
Thread 1 | Thread 2
--------------------------------+------------------------------------
end_bio_extent_writepage() | btrfs_releasepage()
|- spin_lock_irqsave() | |
|- end_page_writeback() | |
| | |- if (PageWriteback() ||...)
| | |- clear_page_extent_mapped()
| | |- kfree(subpage);
|- spin_unlock_irqrestore().
The race can also happen between writeback and btrfs_invalidatepage(),
although that would be much harder as btrfs_invalidatepage() has much
more work to do before the clear_page_extent_mapped() call.
[FIX]
Here we "wait" for the subapge spinlock to be released before we detach
subpage structure.
So this patch will introduce a new function, wait_subpage_spinlock(), to
do the "wait" by acquiring the spinlock and release it.
Since the caller has ensured the page is not dirty nor writeback, and
page is already locked, the only way to hold the subpage spinlock is
from endio function.
Thus we only need to acquire the spinlock to wait for any existing
holder.
Reported-by: Ritesh Harjani <riteshh@linux.ibm.com>
Tested-by: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
When running generic/095, there is a high chance to crash with subpage
data RW support:
assertion failed: PagePrivate(page) && page->private
------------[ cut here ]------------
kernel BUG at fs/btrfs/ctree.h:3403!
Internal error: Oops - BUG: 0 [#1] SMP
CPU: 1 PID: 3567 Comm: fio Tainted: 5.12.0-rc7-custom+ #17
Hardware name: Khadas VIM3 (DT)
Call trace:
assertfail.constprop.0+0x28/0x2c [btrfs]
btrfs_subpage_assert+0x80/0xa0 [btrfs]
btrfs_subpage_set_uptodate+0x34/0xec [btrfs]
btrfs_page_clamp_set_uptodate+0x74/0xa4 [btrfs]
btrfs_dirty_pages+0x160/0x270 [btrfs]
btrfs_buffered_write+0x444/0x630 [btrfs]
btrfs_direct_write+0x1cc/0x2d0 [btrfs]
btrfs_file_write_iter+0xc0/0x160 [btrfs]
new_sync_write+0xe8/0x180
vfs_write+0x1b4/0x210
ksys_pwrite64+0x7c/0xc0
__arm64_sys_pwrite64+0x24/0x30
el0_svc_common.constprop.0+0x70/0x140
do_el0_svc+0x28/0x90
el0_svc+0x2c/0x54
el0_sync_handler+0x1a8/0x1ac
el0_sync+0x170/0x180
Code: f0000160 913be042 913c4000 955444bc (d4210000)
---[ end trace 3fdd39f4cccedd68 ]---
[CAUSE]
Although prepare_pages() calls find_or_create_page(), which returns the
page locked, but in later prepare_uptodate_page() calls, we may call
btrfs_readpage() which will unlock the page before it returns.
This leaves a window where btrfs_releasepage() can sneak in and release
the page, clearing page->private and causing above ASSERT().
[FIX]
In prepare_uptodate_page(), we should not only check page->mapping, but
also PagePrivate() to ensure we are still holding the correct page which
has proper fs context setup.
Reported-by: Ritesh Harjani <riteshh@linux.ibm.com>
Tested-by: Ritesh Harjani <riteshh@linux.ibm.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
RAID56 is not only unsafe due to its write-hole problem, but also has
tons of hardcoded PAGE_SIZE.
Disable it for subpage support for now.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Current submit_extent_page() just checks if the current page range can
be fitted into current bio, and if not, submit then re-add.
But this behavior can't handle subpage case at all.
For subpage case, the problem is in the page size, 64K, which is also
the same size as stripe size.
This means, if we can't fit a full 64K into a bio, due to stripe limit,
then it won't fit into next bio without crossing stripe either.
The proper way to handle it is:
- Check how many bytes we can be put into current bio
- Put as many bytes as possible into current bio first
- Submit current bio
- Create a new bio
- Add the remaining bytes into the new bio
Refactor submit_extent_page() so that it does the above iteration.
The main loop inside submit_extent_page() will look like this:
cur = pg_offset;
while (cur < pg_offset + size) {
u32 offset = cur - pg_offset;
int added;
if (!bio_ctrl->bio) {
/* Allocate new bio if needed */
}
/* Add as many bytes into the bio */
added = btrfs_bio_add_page();
if (added < size - offset) {
/* The current bio is full, submit it */
}
cur += added;
}
Also, since we're doing new bio allocation deep inside the main loop,
extract that code into a new helper, alloc_new_bio().
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
When running the following fsx command (extracted from generic/127) on
subpage filesystem, it can create inline extent with regular extents:
fsx -q -l 262144 -o 65536 -S 191110531 -N 9057 -R -W $mnt/file > /tmp/fsx
The offending extent would look like:
item 9 key (257 INODE_REF 256) itemoff 15703 itemsize 14
index 2 namelen 4 name: file
item 10 key (257 EXTENT_DATA 0) itemoff 14975 itemsize 728
generation 7 type 0 (inline)
inline extent data size 707 ram_bytes 707 compression 0 (none)
item 11 key (257 EXTENT_DATA 4096) itemoff 14922 itemsize 53
generation 7 type 2 (prealloc)
prealloc data disk byte 102346752 nr 4096
prealloc data offset 0 nr 4096
[CAUSE]
For subpage filesystem, the writeback is triggered in page units, which
means, even if we just want to writeback range [16K, 20K) for 64K page
system, we will still try to writeback any dirty sector of range [0, 64K).
This is never a problem if sectorsize == PAGE_SIZE, but for subpage,
this can cause unexpected problems.
For above test case, the last several operations from fsx are:
9055 trunc from 0x40000 to 0x2c3
9057 falloc from 0x164c to 0x19d2 (0x386 bytes)
In operation 9055, we dirtied sector [0, 4096), then in falloc, we call
btrfs_wait_ordered_range(inode, start=4096, len=4096), only expecting to
writeback any dirty data in [4096, 8192), but nothing else.
Unfortunately, in subpage case, above btrfs_wait_ordered_range() will
trigger writeback of the range [0, 64K), which includes the data at
[0, 4096).
And since at the call site, we haven't yet increased i_size, which is
still 707, this means cow_file_range() can insert an inline extent.
Resulting above inline + regular extent.
[WORKAROUND]
I don't really have any good short-term solution yet, as this means all
operations that would trigger writeback need to be reviewed for any
i_size change.
So here I choose to disable inline extent creation for subpage case as a
workaround. We have done tons of work just to avoid such extent, so I
don't to create an exception just for subpage.
This only affects inline extent creation, subpage has no problem reading
existing inline extents at all.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
When running fsstress with subpage RW support, there are random
BUG_ON()s triggered with the following trace:
kernel BUG at fs/btrfs/file-item.c:667!
Internal error: Oops - BUG: 0 [#1] SMP
CPU: 1 PID: 3486 Comm: kworker/u13:2 5.11.0-rc4-custom+ #43
Hardware name: Radxa ROCK Pi 4B (DT)
Workqueue: btrfs-worker-high btrfs_work_helper [btrfs]
pstate: 60000005 (nZCv daif -PAN -UAO -TCO BTYPE=--)
pc : btrfs_csum_one_bio+0x420/0x4e0 [btrfs]
lr : btrfs_csum_one_bio+0x400/0x4e0 [btrfs]
Call trace:
btrfs_csum_one_bio+0x420/0x4e0 [btrfs]
btrfs_submit_bio_start+0x20/0x30 [btrfs]
run_one_async_start+0x28/0x44 [btrfs]
btrfs_work_helper+0x128/0x1b4 [btrfs]
process_one_work+0x22c/0x430
worker_thread+0x70/0x3a0
kthread+0x13c/0x140
ret_from_fork+0x10/0x30
[CAUSE]
Above BUG_ON() means there is some bio range which doesn't have ordered
extent, which indeed is worth a BUG_ON().
Unlike regular sectorsize == PAGE_SIZE case, in subpage we have extra
subpage dirty bitmap to record which range is dirty and should be
written back.
This means, if we submit bio for a subpage range, we do not only need to
clear page dirty, but also need to clear subpage dirty bits.
In __extent_writepage_io(), we will call btrfs_page_clear_dirty() for
any range we submit a bio.
But there is loophole, if we hit a range which is beyond i_size, we just
call btrfs_writepage_endio_finish_ordered() to finish the ordered io,
then break out, without clearing the subpage dirty.
This means, if we hit above branch, the subpage dirty bits are still
there, if other range of the page get dirtied and we need to writeback
that page again, we will submit bio for the old range, leaving a wild
bio range which doesn't have ordered extent.
[FIX]
Fix it by always calling btrfs_page_clear_dirty() in
__extent_writepage_io().
Also to avoid such problem from happening again, add a new assert,
btrfs_page_assert_not_dirty(), to make sure both page dirty and subpage
dirty bits are cleared before exiting __extent_writepage_io().
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
For subpage case, one page of data reloc inode can contain several file
extents, like this:
|<--- File extent A --->| FE B | FE C |<--- File extent D -->|
|<--------- Page --------->|
We can no longer use PAGE_SIZE directly for various operations.
This patch will relocate_one_page() to handle subpage case by:
- Iterating through all extents of a cluster when marking pages
When marking pages dirty and delalloc, we need to check the cluster
extent boundary.
Now we introduce a loop to go extent by extent of a page, until we
either finished the last extent, or reach the page end.
By this, regular sectorsize == PAGE_SIZE can still work as usual, since
we will do that loop only once.
- Iteration start from max(page_start, extent_start)
Since we can have the following case:
| FE B | FE C |<--- File extent D -->|
|<--------- Page --------->|
Thus we can't always start from page_start, but do a
max(page_start, extent_start)
- Iteration end when the cluster is exhausted
Similar to previous case, the last file extent can end before the page
end:
|<--- File extent A --->| FE B | FE C |
|<--------- Page --------->|
In this case, we need to manually exit the loop after we have finished
the last extent of the cluster.
- Reserve metadata space for each extent range
Since now we can hit multiple ranges in one page, we should reserve
metadata for each range, not simply PAGE_SIZE.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In function relocate_file_extent_cluster(), we have a big loop for
marking all involved page delalloc.
That part is long enough to be contained in one function, so this patch
will move that code chunk into a new function, relocate_one_page().
This also provides enough space for later subpage work.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
For the initial subpage support, although we won't support compressed
write, we still need to support compressed read.
But for lzo_decompress_bio() it has several problems:
- The abuse of PAGE_SIZE for boundary detection
For subpage case, we should follow sectorsize to detect the padding
zeros.
Using PAGE_SIZE will cause subpage compress read to skip certain
bytes, and causing read error.
- Too many helper variables
There are half a dozen helper variables, which is only making things
harder to read
This patch will rework lzo_decompress_bio() to make it work for subpage:
- Use sectorsize to do boundary check, while still use PAGE_SIZE for
page switching
This allows us to have the same on-disk format for 4K sectorsize fs,
while take advantage of larger page size.
- Use two main cursors
Only @cur_in and @cur_out is utilized as the main cursor.
The helper variables will only be declared inside the loop, and only 2
helper variables needed.
- Introduce a helper function to copy compressed segment payload
Introduce a new helper, copy_compressed_segment(), to copy a
compressed segment to workspace buffer.
This function will handle the page switching.
Now the net result is, with all the excessive comments and new helper
function, the refactored code is still smaller, and easier to read.
For other decompression code, they have no special padding rule, thus no
need to bother for initial subpage support, but will be refactored to
the same style later.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There are several bugs inside the function btrfs_decompress_buf2page()
- @start_byte doesn't take bvec.bv_offset into consideration
Thus it can't handle case where the target range is not page aligned.
- Too many helper variables
There are tons of helper variables, @buf_offset, @current_buf_start,
@start_byte, @prev_start_byte, @working_bytes, @bytes.
This hurts anyone who wants to read the function.
- No obvious main cursor for the iteartion
A new problem caused by previous problem.
- Comments for parameter list makes no sense
Like @buf_start is the offset to @buf, or offset inside the full
decompressed extent? (Spoiler alert, the later case)
And @total_out acts more like @buf_start + @size_of_buf.
The worst is @disk_start.
The real meaning of it is the file offset of the full decompressed
extent.
This patch will rework the whole function by:
- Add a proper comment with ASCII art to explain the parameter list
- Rework parameter list
The old @buf_start is renamed to @decompressed, to show how many bytes
are already decompressed inside the full decompressed extent.
The old @total_out is replaced by @buf_len, which is the decompressed
data size.
For old @disk_start and @bio, just pass @compressed_bio in.
- Use single main cursor
The main cursor will be @cur_file_offset, to show what's the current
file offset.
Other helper variables will be declared inside the main loop, and only
minimal amount of helper variables:
* offset_inside_decompressed_buf: The only real helper
* copy_start_file_offset: File offset we start memcpy
* bvec_file_offset: File offset of current bvec
Even with all these extensive comments, the final function is still
smaller than the original function, which is definitely a win.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
When subpage compressed read write support is enabled, btrfs/038 always
fails with EIO.
A simplified script can easily trigger the problem:
mkfs.btrfs -f -s 4k $dev
mount $dev $mnt -o compress=lzo
xfs_io -f -c "truncate 118811" $mnt/foo
xfs_io -c "pwrite -S 0x0d -b 39987 92267 39987" $mnt/foo > /dev/null
sync
btrfs subvolume snapshot -r $mnt $mnt/mysnap1
xfs_io -c "pwrite -S 0x3e -b 80000 200000 80000" $mnt/foo > /dev/null
sync
xfs_io -c "pwrite -S 0xdc -b 10000 250000 10000" $mnt/foo > /dev/null
xfs_io -c "pwrite -S 0xff -b 10000 300000 10000" $mnt/foo > /dev/null
sync
btrfs subvolume snapshot -r $mnt $mnt/mysnap2
cat $mnt/mysnap2/foo
# Above cat will fail due to EIO
[CAUSE]
The problem is in btrfs_submit_compressed_read().
When it tries to grab the extent map of the read range, it uses the
following call:
em = lookup_extent_mapping(em_tree,
page_offset(bio_first_page_all(bio)),
fs_info->sectorsize);
The problem is in the page_offset(bio_first_page_all(bio)) part.
The offending inode has the following file extent layout
item 10 key (257 EXTENT_DATA 131072) itemoff 15639 itemsize 53
generation 8 type 1 (regular)
extent data disk byte 13680640 nr 4096
extent data offset 0 nr 4096 ram 4096
extent compression 0 (none)
item 11 key (257 EXTENT_DATA 135168) itemoff 15586 itemsize 53
generation 8 type 1 (regular)
extent data disk byte 0 nr 0
item 12 key (257 EXTENT_DATA 196608) itemoff 15533 itemsize 53
generation 8 type 1 (regular)
extent data disk byte 13676544 nr 4096
extent data offset 0 nr 53248 ram 86016
extent compression 2 (lzo)
And the bio passed in has the following parameters:
page_offset(bio_first_page_all(bio)) = 131072
bio_first_bvec_all(bio)->bv_offset = 65536
If we use page_offset(bio_first_page_all(bio) without adding bv_offset,
we will get an extent map for file offset 131072, not 196608.
This means we read uncompressed data from disk, and later decompression
will definitely fail.
[FIX]
Take bv_offset into consideration when trying to grab an extent map.
And add an ASSERT() to ensure we're really getting a compressed extent.
Thankfully this won't affect anything but subpage, thus we only need to
ensure this patch get merged before we enabled basic subpage support.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
For current subpage support, we only support 64K page size with 4K
sector size.
This makes compressed readahead less effective, as maximum compressed
extent size is only 128K, 2x the page size.
On the other hand, the function add_ra_bio_pages() is still assuming
sectorsize == PAGE_SIZE, and code change may affect 4K page size
systems.
So for now, let's disable subpage compressed readahead for now.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
When testing experimental subpage compressed write support, it hits a
NULL pointer dereference inside read path:
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000018
pc : __pi_memcmp+0x28/0x1ec
lr : check_data_csum+0xd0/0x274 [btrfs]
Call trace:
__pi_memcmp+0x28/0x1ec
btrfs_verify_data_csum+0xf4/0x244 [btrfs]
end_bio_extent_readpage+0x1d0/0x6b0 [btrfs]
bio_endio+0x15c/0x1dc
end_workqueue_fn+0x44/0x64 [btrfs]
btrfs_work_helper+0x74/0x250 [btrfs]
process_one_work+0x1d4/0x47c
worker_thread+0x180/0x400
kthread+0x11c/0x120
ret_from_fork+0x10/0x30
Code: 54000261 d100044c d343fd8c f8408403 (f8408424)
---[ end trace 9e2c59f33ea40866 ]---
[CAUSE]
When reading two compressed extents inside the same page, like the
following layout, we trigger above crash:
0 32K 64K
|-------|\\\\\\\|
| \- Compressed extent (A)
\--------- Compressed extent (B)
For compressed read, we don't need to populate its io_bio->csum, as we
rely on compressed_bio->csum to verify the compressed data, and then
copy the decompressed to inode pages.
Normally btrfs_verify_data_csum() skip such page by checking and
clearing its PageChecked flag
But since that flag is still for the full page, when endio for inode
page range [0, 32K) gets executed, it clears PageChecked flag for the
full page.
Then when endio for inode page range [32K, 64K) gets executed, since the
page no longer has PageChecked flag, it just continues checking, even
though io_bio->csum is NULL.
[FIX]
Thankfully there are only two users of PageChecked bit:
- Cow fixup
Since subpage has its own way to trace page dirty (dirty_bitmap) and
ordered bit (ordered_bitmap), it should never trigger cow fixup.
- Compressed read
We can distinguish such read by just checking io_bio->csum.
So just check io_bio->csum before doing the verification to avoid such
NULL pointer dereference.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In btrfs_do_readpage(), we never reset @this_bio_flag after we hit a
compressed extent.
This is fine, as for PAGE_SIZE == sectorsize case, we can only have one
sector for one page, thus @this_bio_flag will only be set at most once.
But for subpage case, after hitting a compressed extent, @this_bio_flag
will always have EXTENT_BIO_COMPRESSED bit, even we're reading a regular
extent.
This will lead to various read errors, and causing new ASSERT() in
incoming subpage patches, which adds more strict check in
btrfs_submit_compressed_read().
Fix it by declaring @this_bio_flag inside the main loop and reset its
value for each iteration.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Comparators just read the data and thus get const parameters. This
should be also preserved by the local variables, update all comparators
passed to sort or bsearch.
Cleanups:
- unnecessary casts are dropped
- btrfs_cmp_device_free_bytes is cleaned up to follow the common pattern
and 'inline' is dropped as the function address is taken
Signed-off-by: David Sterba <dsterba@suse.com>
There are two helpers doing the same calculations based on nparity and
ncopies. calc_data_stripes can be simplified into one expression, so far
we don't have profile with both copies and parity, so there's no
effective change. calc_stripe_length should reuse the helper and not
repeat the same calculation.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The device allocation is split to two functions, but one just calls the
other and they're very far in the file. Merge them together.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
