Commit 780f66e5 authored Feb 17, 2020 by zhangyi (F) Committed by Theodore Ts'o Mar 05, 2020

jbd2: improve comments about freeing data buffers whose page mapping is NULL

Improve comments in jbd2_journal_commit_transaction() to describe why
we don't need to clear the buffer_mapped bit for freeing file mapping
buffers whose page mapping is NULL.

Link: https://lore.kernel.org/r/20200217112706.20085-1-yi.zhang@huawei.com


Fixes: c96dceea ("jbd2: do not clear the BH_Mapped flag when forgetting a metadata buffer")
Suggested-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: zhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

parent 6cfb061f

fs/jbd2/commit.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -997,9 +997,10 @@ restart_loop:
		* journalled data) we need to unmap buffer and clear
		* more bits. We also need to be careful about the check
		* because the data page mapping can get cleared under
		* out hands, which alse need not to clear more bits
		* because the page and buffers will be freed and can
		* never be reused once we are done with them.
		* our hands. Note that if mapping == NULL, we don't
		* need to make buffer unmapped because the page is
		* already detached from the mapping and buffers cannot
		* get reused.
		*/
		mapping = READ_ONCE(bh->b_page->mapping);
		if (mapping && !sb_is_blkdev_sb(mapping->host->i_sb)) {

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