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0cf9b244e7
linux/fs/btrfs
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Qu Wenruo 0cf9b244e7 btrfs: subpage: only allow compression if the range is fully page aligned 
For compressed write, we use a mechanism called async COW, which unlike
regular run_delalloc_cow() or cow_file_range() will also unlock the
first page.

This mechanism allows us to continue handling next ranges, without
waiting for the time consuming compression.

But this has a problem for subpage case, as we could have the following
delalloc range for a page:

0		32K		64K
|	|///////|	|///////|
		\- A		\- B

In the above case, if we pass both ranges to cow_file_range_async(),
both range A and range B will try to unlock the full page [0, 64K).

And which one finishes later than the other one will try to do other
page operations like end_page_writeback() on a unlocked page, triggering
VM layer BUG_ON().

To make subpage compression work at least partially, here we add another
restriction for it, only allow compression if the delalloc range is
fully page aligned.

By that, async extent is always ensured to unlock the first page
exclusively, just like it used to be for regular sectorsize.

In theory, we only need to make sure the delalloc range fully covers its
first page, but the tail page will be locked anyway, blocking later
writeback until the compression finishes.

Thus here we choose to make sure the range is fully page aligned before
doing the compression.

In the future, we could optimize the situation by properly increasing
subpage::writers number for the locked page, but that also means we need
to change how we run delalloc range of page.
(Instead of running each delalloc range we hit, we need to find and lock
all delalloc ranges covering the page, then run each of them).

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2021-10-26 19:08:05 +02:00
..
tests btrfs: subpage: avoid potential deadlock with compression and delalloc 2021-10-26 19:08:05 +02:00
acl.c overlayfs update for 5.15 2021-09-02 09:21:27 -07:00
async-thread.c Btrfs: fix crash during unmount due to race with delayed inode workers 2020-03-23 17:01:51 +01:00
async-thread.h Btrfs: fix crash during unmount due to race with delayed inode workers 2020-03-23 17:01:51 +01:00
backref.c btrfs: remove ignore_offset argument from btrfs_find_all_roots() 2021-08-23 13:19:01 +02:00
backref.h btrfs: remove ignore_offset argument from btrfs_find_all_roots() 2021-08-23 13:19:01 +02:00
block-group.c btrfs: zoned: add a dedicated data relocation block group 2021-10-26 19:08:01 +02:00
block-group.h btrfs: zoned: implement active zone tracking 2021-10-26 19:07:59 +02:00
block-rsv.c btrfs: introduce mount option rescue=ignorebadroots 2020-12-08 15:53:41 +01:00
block-rsv.h btrfs: Remove __ prefix from btrfs_block_rsv_release 2020-03-23 17:01:55 +01:00
btrfs_inode.h btrfs: keep track of the last logged keys when logging a directory 2021-10-26 19:08:02 +02:00
check-integrity.c btrfs: rename struct btrfs_io_bio to btrfs_bio 2021-10-26 19:08:02 +02:00
check-integrity.h btrfs: remove btrfsic_submit_bh() 2020-03-23 17:01:39 +01:00
compression.c btrfs: subpage: make end_compressed_bio_writeback() compatible 2021-10-26 19:08:04 +02:00
compression.h btrfs: determine stripe boundary at bio allocation time in btrfs_submit_compressed_write 2021-10-26 19:08:04 +02:00
ctree.c btrfs: unexport setup_items_for_insert() 2021-10-26 19:08:03 +02:00
ctree.h btrfs: remove unused function btrfs_bio_fits_in_stripe() 2021-10-26 19:08:04 +02:00
delalloc-space.c btrfs: fix typos in comments 2021-06-22 14:11:57 +02:00
delalloc-space.h btrfs: make btrfs_delalloc_reserve_space take btrfs_inode 2020-07-27 12:55:36 +02:00
delayed-inode.c btrfs: loop only once over data sizes array when inserting an item batch 2021-10-26 19:08:03 +02:00
delayed-inode.h btrfs: make btrfs_delayed_update_inode take btrfs_inode 2020-12-08 15:54:10 +01:00
delayed-ref.c btrfs: fix lock inversion problem when doing qgroup extent tracing 2021-07-22 15:50:07 +02:00
delayed-ref.h btrfs: only let one thread pre-flush delayed refs in commit 2021-02-08 22:58:56 +01:00
dev-replace.c btrfs: fix typos in comments 2021-06-22 14:11:57 +02:00
dev-replace.h btrfs: zoned: mark block groups to copy for device-replace 2021-02-09 02:46:07 +01:00
dir-item.c btrfs: unify lookup return value when dir entry is missing 2021-10-07 22:06:32 +02:00
discard.c btrfs: fix typos in comments 2021-06-22 14:11:57 +02:00
discard.h btrfs: cleanup btrfs_discard_update_discardable usage 2020-12-08 15:54:02 +01:00
disk-io.c btrfs: assert that extent buffers are write locked instead of only locked 2021-10-26 19:08:02 +02:00
disk-io.h btrfs: rename struct btrfs_io_bio to btrfs_bio 2021-10-26 19:08:02 +02:00
export.c btrfs: locking: rip out path->leave_spinning 2020-12-08 15:54:02 +01:00
export.h btrfs: export helpers for subvolume name/id resolution 2020-03-23 17:01:42 +01:00
extent_io.c btrfs: subpage: avoid potential deadlock with compression and delalloc 2021-10-26 19:08:05 +02:00
extent_io.h btrfs: cleanup for extent_write_locked_range() 2021-10-26 19:08:04 +02:00
extent_map.c btrfs: rename btrfs_bio to btrfs_io_context 2021-10-26 19:08:02 +02:00
extent_map.h btrfs: remove extent_map::bdev 2019-11-18 23:43:44 +01:00
extent-io-tree.h btrfs: use fixed width int type for extent_state::state 2020-12-08 15:54:13 +01:00
extent-tree.c btrfs: assert that extent buffers are write locked instead of only locked 2021-10-26 19:08:02 +02:00
file-item.c btrfs: rename struct btrfs_io_bio to btrfs_bio 2021-10-26 19:08:02 +02:00
file.c btrfs: subpage: add bitmap for PageChecked flag 2021-10-26 19:08:03 +02:00
free-space-cache.c btrfs: subpage: add bitmap for PageChecked flag 2021-10-26 19:08:03 +02:00
free-space-cache.h btrfs: zoned: track unusable bytes for zones 2021-02-09 02:46:03 +01:00
free-space-tree.c btrfs: fix possible free space tree corruption with online conversion 2021-01-25 18:44:37 +01:00
free-space-tree.h btrfs: rename btrfs_block_group_cache 2019-11-18 17:51:51 +01:00
inode-item.c btrfs: locking: rip out path->leave_spinning 2020-12-08 15:54:02 +01:00
inode.c btrfs: subpage: only allow compression if the range is fully page aligned 2021-10-26 19:08:05 +02:00
ioctl.c btrfs: defrag: enable defrag for subpage case 2021-10-26 19:07:58 +02:00
Kconfig btrfs: disable build on platforms having page size 256K 2021-06-22 14:11:57 +02:00
locking.c btrfs: fix typos in comments 2021-06-22 14:11:57 +02:00
locking.h btrfs: assert that extent buffers are write locked instead of only locked 2021-10-26 19:08:02 +02:00
lzo.c btrfs: subpage: make lzo_compress_pages() compatible 2021-10-26 19:08:05 +02:00
Makefile btrfs: initial fsverity support 2021-08-23 13:19:09 +02:00
misc.h btrfs: use correct header for div_u64 in misc.h 2021-09-07 14:29:50 +02:00
ordered-data.c btrfs: zoned: fix double counting of split ordered extent 2021-09-07 14:30:41 +02:00
ordered-data.h btrfs: remove uptodate parameter from btrfs_dec_test_first_ordered_pending 2021-08-23 13:19:02 +02:00
orphan.c
print-tree.c btrfs: print the actual offset in btrfs_root_name 2021-01-07 17:25:05 +01:00
print-tree.h btrfs: print the actual offset in btrfs_root_name 2021-01-07 17:25:05 +01:00
props.c btrfs: props: change how empty value is interpreted 2021-06-22 14:11:58 +02:00
props.h btrfs: delete unused function btrfs_set_prop_trans 2019-04-29 19:02:54 +02:00
qgroup.c btrfs: remove ignore_offset argument from btrfs_find_all_roots() 2021-08-23 13:19:01 +02:00
qgroup.h btrfs: fix lock inversion problem when doing qgroup extent tracing 2021-07-22 15:50:07 +02:00
raid56.c btrfs: remove btrfs_raid_bio::fs_info member 2021-10-26 19:08:03 +02:00
raid56.h btrfs: remove btrfs_raid_bio::fs_info member 2021-10-26 19:08:03 +02:00
rcu-string.h btrfs: rcu-string: Replace zero-length array with flexible-array member 2020-03-23 17:01:53 +01:00
reada.c btrfs: rename btrfs_bio to btrfs_io_context 2021-10-26 19:08:02 +02:00
ref-verify.c btrfs: stop doing GFP_KERNEL memory allocations in the ref verify tool 2021-08-23 13:19:00 +02:00
ref-verify.h
reflink.c btrfs: subpage: add bitmap for PageChecked flag 2021-10-26 19:08:03 +02:00
reflink.h Btrfs: move all reflink implementation code into its own file 2020-03-23 17:01:54 +01:00
relocation.c btrfs: rename setup_extent_mapping in relocation code 2021-10-26 19:08:01 +02:00
root-tree.c btrfs: qgroup: fix qgroup meta rsv leak for subvolume operations 2020-10-07 12:12:13 +02:00
scrub.c btrfs: remove btrfs_raid_bio::fs_info member 2021-10-26 19:08:03 +02:00
send.c btrfs: send: simplify send_create_inode_if_needed 2021-10-25 21:17:16 +02:00
send.h btrfs: send: avoid copying file data 2020-10-07 12:13:17 +02:00
space-info.c btrfs: prevent __btrfs_dump_space_info() to underflow its free space 2021-09-17 19:29:54 +02:00
space-info.h btrfs: rip out btrfs_space_info::total_bytes_pinned 2021-06-22 14:55:25 +02:00
struct-funcs.c btrfs: add special case to setget helpers for 64k pages 2021-08-23 13:18:58 +02:00
subpage.c btrfs: handle page locking in btrfs_page_end_writer_lock with no writers 2021-10-26 19:08:05 +02:00
subpage.h btrfs: rework page locking in __extent_writepage() 2021-10-26 19:08:05 +02:00
super.c btrfs: use latest_dev in btrfs_show_devname 2021-10-26 19:08:00 +02:00
sysfs.c btrfs: sysfs: document structures and their associated files 2021-08-23 13:19:12 +02:00
sysfs.h btrfs: split and refactor btrfs_sysfs_remove_devices_dir 2020-10-07 12:12:21 +02:00
transaction.c btrfs: rework chunk allocation to avoid exhaustion of the system chunk array 2021-07-07 17:42:41 +02:00
transaction.h btrfs: rework chunk allocation to avoid exhaustion of the system chunk array 2021-07-07 17:42:41 +02:00
tree-checker.c btrfs: add ro compat flags to inodes 2021-08-23 13:19:09 +02:00
tree-checker.h
tree-defrag.c btrfs: locking: remove all the blocking helpers 2020-12-08 15:54:01 +01:00
tree-log.c btrfs: use single bulk copy operations when logging directories 2021-10-26 19:08:03 +02:00
tree-log.h btrfs: keep track of the last logged keys when logging a directory 2021-10-26 19:08:02 +02:00
tree-mod-log.c btrfs: fix race when picking most recent mod log operation for an old root 2021-04-20 19:27:17 +02:00
tree-mod-log.h btrfs: add and use helper to get lowest sequence number for the tree mod log 2021-04-19 17:25:17 +02:00
ulist.c
ulist.h
uuid-tree.c btrfs: remove unnecessary casts in printk 2020-12-08 15:53:52 +01:00
verity.c btrfs: fix transaction handle leak after verity rollback failure 2021-09-17 19:29:41 +02:00
volumes.c btrfs: remove btrfs_raid_bio::fs_info member 2021-10-26 19:08:03 +02:00
volumes.h btrfs: rename struct btrfs_io_bio to btrfs_bio 2021-10-26 19:08:02 +02:00
xattr.c btrfs: assert that extent buffers are write locked instead of only locked 2021-10-26 19:08:02 +02:00
xattr.h
zlib.c btrfs: rework btrfs_decompress_buf2page() 2021-08-23 13:19:04 +02:00
zoned.c btrfs: rename btrfs_bio to btrfs_io_context 2021-10-26 19:08:02 +02:00
zoned.h btrfs: zoned: add a dedicated data relocation block group 2021-10-26 19:08:01 +02:00
zstd.c btrfs: rework btrfs_decompress_buf2page() 2021-08-23 13:19:04 +02:00