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7703bdd8d2
linux/fs/btrfs
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Chris Mason 7703bdd8d2 Btrfs: don't clean dirty pages during buffered writes 
During buffered writes, we follow this basic series of steps:

again:
	lock all the pages
	wait for writeback on all the pages
	Take the extent range lock
	wait for ordered extents on the whole range
	clean all the pages

	if (copy_from_user_in_atomic() hits a fault) {
		drop our locks
		goto again;
	}

	dirty all the pages
	release all the locks

The extra waiting, cleaning and locking are there to make sure we don't
modify pages in flight to the drive, after they've been crc'd.

If some of the pages in the range were already dirty when the write
began, and we need to goto again, we create a window where a dirty page
has been cleaned and unlocked.  It may be reclaimed before we're able to
lock it again, which means we'll read the old contents off the drive and
lose any modifications that had been pending writeback.

We don't actually need to clean the pages.  All of the other locking in
place makes sure we don't start IO on the pages, so we can just leave
them dirty for the duration of the write.

Fixes: 73d59314e6 (the original btrfs merge)
CC: stable@vger.kernel.org # v4.4+
Signed-off-by: Chris Mason <clm@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-10-15 17:23:35 +02:00
..
tests btrfs: tests: add separate stub for find_lock_delalloc_range 2018-10-15 17:23:34 +02:00
acl.c btrfs: remove unnecessary curly braces in btrfs_get_acl 2018-08-06 13:12:41 +02:00
async-thread.c btrfs: replace GPL boilerplate by SPDX -- sources 2018-04-12 16:29:51 +02:00
async-thread.h btrfs: replace GPL boilerplate by SPDX -- headers 2018-04-12 16:29:46 +02:00
backref.c Btrfs: preftree: use rb_first_cached 2018-10-15 17:23:33 +02:00
backref.h btrfs: replace GPL boilerplate by SPDX -- headers 2018-04-12 16:29:46 +02:00
btrfs_inode.h btrfs: Remove 'objectid' member from struct btrfs_root 2018-10-15 17:23:25 +02:00
check-integrity.c Btrfs: use args in the correct order for kcalloc in btrfsic_read_block 2018-10-15 17:23:30 +02:00
check-integrity.h btrfs: replace GPL boilerplate by SPDX -- headers 2018-04-12 16:29:46 +02:00
compression.c btrfs: remove unused pointer 'tree' in btrfs_submit_compressed_read 2018-10-15 17:23:28 +02:00
compression.h btrfs: compression: Add linux/sizes.h for compression.h 2018-05-29 18:13:00 +02:00
ctree.c btrfs: handle error of get_old_root 2018-10-15 17:23:31 +02:00
ctree.h btrfs: tests: polish ifdefs around testing helper 2018-10-15 17:23:34 +02:00
dedupe.h btrfs: replace GPL boilerplate by SPDX -- headers 2018-04-12 16:29:46 +02:00
delayed-inode.c Btrfs: delayed-inode: use rb_first_cached for ins_root and del_root 2018-10-15 17:23:33 +02:00
delayed-inode.h Btrfs: delayed-inode: use rb_first_cached for ins_root and del_root 2018-10-15 17:23:33 +02:00
delayed-ref.c Btrfs: delayed-refs: use rb_first_cached for ref_tree 2018-10-15 17:23:33 +02:00
delayed-ref.h Btrfs: delayed-refs: use rb_first_cached for ref_tree 2018-10-15 17:23:33 +02:00
dev-replace.c btrfs: fix error handling in btrfs_dev_replace_start 2018-10-15 17:23:31 +02:00
dev-replace.h btrfs: replace GPL boilerplate by SPDX -- headers 2018-04-12 16:29:46 +02:00
dir-item.c btrfs: Remove root parameter from btrfs_insert_dir_item 2018-10-15 17:23:25 +02:00
disk-io.c Btrfs: delayed-refs: use rb_first_cached for ref_tree 2018-10-15 17:23:33 +02:00
disk-io.h btrfs: unify end_io callbacks of async_submit_bio 2018-08-06 13:12:55 +02:00
export.c btrfs: Remove 'objectid' member from struct btrfs_root 2018-10-15 17:23:25 +02:00
export.h btrfs: replace GPL boilerplate by SPDX -- headers 2018-04-12 16:29:46 +02:00
extent_io.c btrfs: tests: add separate stub for find_lock_delalloc_range 2018-10-15 17:23:34 +02:00
extent_io.h btrfs: tests: add separate stub for find_lock_delalloc_range 2018-10-15 17:23:34 +02:00
extent_map.c Btrfs: extent_map: use rb_first_cached 2018-10-15 17:23:33 +02:00
extent_map.h Btrfs: extent_map: use rb_first_cached 2018-10-15 17:23:33 +02:00
extent-tree.c btrfs: refactor __btrfs_run_delayed_refs loop 2018-10-15 17:23:35 +02:00
file-item.c btrfs: simplify pointer chasing of local fs_info variables 2018-08-06 13:12:43 +02:00
file.c Btrfs: don't clean dirty pages during buffered writes 2018-10-15 17:23:35 +02:00
free-space-cache.c btrfs: remove unneeded NULL checks before kfree 2018-10-15 17:23:26 +02:00
free-space-cache.h btrfs: replace GPL boilerplate by SPDX -- headers 2018-04-12 16:29:46 +02:00
free-space-tree.c btrfs: Remove fs_info from btrfs_del_root 2018-08-06 13:13:00 +02:00
free-space-tree.h btrfs: Remove fs_info argument from add_to_free_space_tree 2018-05-28 18:07:36 +02:00
inode-item.c btrfs: replace GPL boilerplate by SPDX -- sources 2018-04-12 16:29:51 +02:00
inode-map.c btrfs: prune unused includes 2018-08-06 13:12:43 +02:00
inode-map.h btrfs: replace GPL boilerplate by SPDX -- headers 2018-04-12 16:29:46 +02:00
inode.c Btrfs: extent_map: use rb_first_cached 2018-10-15 17:23:33 +02:00
ioctl.c btrfs: Ensure btrfs_trim_fs can trim the whole filesystem 2018-10-15 17:23:32 +02:00
Kconfig btrfs: add SPDX header to Kconfig 2018-04-12 16:29:55 +02:00
locking.c btrfs: replace waitqueue_actvie with cond_wake_up 2018-05-28 18:23:09 +02:00
locking.h btrfs: replace GPL boilerplate by SPDX -- headers 2018-04-12 16:29:46 +02:00
lzo.c btrfs: lzo: Harden inline lzo compressed extent decompression 2018-05-30 16:46:43 +02:00
Makefile btrfs: Remove custom crc32c init code 2018-03-26 15:09:39 +02:00
math.h btrfs: replace GPL boilerplate by SPDX -- headers 2018-04-12 16:29:46 +02:00
ordered-data.c btrfs: prune unused includes 2018-08-06 13:12:43 +02:00
ordered-data.h btrfs: remove remaing full_sync logic from btrfs_sync_file 2018-08-06 13:12:31 +02:00
orphan.c btrfs: replace GPL boilerplate by SPDX -- sources 2018-04-12 16:29:51 +02:00
print-tree.c btrfs: annotate unlikely branches after V0 extent type removal 2018-08-06 13:12:41 +02:00
print-tree.h btrfs: print-tree: debugging output enhancement 2018-04-20 19:18:16 +02:00
props.c btrfs: property: Set incompat flag if lzo/zstd compression is set 2018-05-17 14:18:25 +02:00
props.h btrfs: replace GPL boilerplate by SPDX -- headers 2018-04-12 16:29:46 +02:00
qgroup.c btrfs: qgroup: Dirty all qgroups before rescan 2018-10-15 17:23:26 +02:00
qgroup.h btrfs: qgroup: Drop fs_info parameter from btrfs_qgroup_inherit 2018-08-06 13:12:53 +02:00
raid56.c btrfs: raid56: catch errors from full_stripe_write 2018-08-06 13:12:45 +02:00
raid56.h btrfs: replace GPL boilerplate by SPDX -- headers 2018-04-12 16:29:46 +02:00
rcu-string.h btrfs: replace GPL boilerplate by SPDX -- headers 2018-04-12 16:29:46 +02:00
reada.c btrfs: prune unused includes 2018-08-06 13:12:43 +02:00
ref-verify.c btrfs: Remove 'objectid' member from struct btrfs_root 2018-10-15 17:23:25 +02:00
ref-verify.h btrfs: replace GPL boilerplate by SPDX -- headers 2018-04-12 16:29:46 +02:00
relocation.c btrfs: Handle owner mismatch gracefully when walking up tree 2018-10-15 17:23:27 +02:00
root-tree.c btrfs: Remove fs_info from btrfs_add_root_ref 2018-08-06 13:13:00 +02:00
scrub.c Btrfs: clean up scrub is_dev_replace parameter 2018-10-15 17:23:26 +02:00
send.c Btrfs: unify error handling of btrfs_lookup_dir_item 2018-10-15 17:23:30 +02:00
send.h btrfs: replace GPL boilerplate by SPDX -- headers 2018-04-12 16:29:46 +02:00
struct-funcs.c btrfs: prune unused includes 2018-08-06 13:12:43 +02:00
super.c btrfs: Remove 'objectid' member from struct btrfs_root 2018-10-15 17:23:25 +02:00
sysfs.c btrfs: prune unused includes 2018-08-06 13:12:43 +02:00
sysfs.h btrfs: sysfs: Use enum/define value for feature array definitions 2018-05-28 18:23:39 +02:00
transaction.c Btrfs: delayed-refs: use rb_first_cached for href_root 2018-10-15 17:23:33 +02:00
transaction.h btrfs: replace get_seconds with new 64bit time API 2018-08-06 13:12:29 +02:00
tree-checker.c btrfs: tree-checker: Detect invalid and empty essential trees 2018-08-06 13:12:42 +02:00
tree-checker.h btrfs: replace GPL boilerplate by SPDX -- headers 2018-04-12 16:29:46 +02:00
tree-defrag.c btrfs: replace GPL boilerplate by SPDX -- sources 2018-04-12 16:29:51 +02:00
tree-log.c btrfs: fix error handling in free_log_tree 2018-10-15 17:23:29 +02:00
tree-log.h btrfs: change btrfs_pin_log_trans to return void 2018-10-15 17:23:27 +02:00
ulist.c btrfs: replace GPL boilerplate by SPDX -- sources 2018-04-12 16:29:51 +02:00
ulist.h btrfs: replace GPL boilerplate by SPDX -- headers 2018-04-12 16:29:46 +02:00
uuid-tree.c btrfs: Remove fs_info argument from btrfs_uuid_tree_rem 2018-05-30 16:46:53 +02:00
volumes.c btrfs: use common helper instead of open coding a bit test 2018-10-15 17:23:35 +02:00
volumes.h btrfs: Make btrfs_find_device_by_devspec return btrfs_device directly 2018-10-15 17:23:30 +02:00
xattr.c btrfs: replace GPL boilerplate by SPDX -- sources 2018-04-12 16:29:51 +02:00
xattr.h btrfs: replace GPL boilerplate by SPDX -- headers 2018-04-12 16:29:46 +02:00
zlib.c btrfs: replace GPL boilerplate by SPDX -- sources 2018-04-12 16:29:51 +02:00
zstd.c btrfs: replace GPL boilerplate by SPDX -- sources 2018-04-12 16:29:51 +02:00