Commit 147d4a09 authored by Ritesh Harjani (IBM)'s avatar Ritesh Harjani (IBM) Committed by Theodore Ts'o
Browse files

jbd2: Remove page size assumptions 



jbd2_alloc() allocates a buffer from slab when the block size is smaller
than PAGE_SIZE, and slab may be using a compound page.  Before commit
8147c4c4, we set b_page to the precise page containing the buffer
and this code worked well.  Now we set b_page to the head page of the
allocation, so we can no longer use offset_in_page().  While we could
do a 1:1 replacement with offset_in_folio(), use the more idiomatic
bh_offset() and the folio APIs to map the buffer.

This isn't enough to support a b_size larger than PAGE_SIZE on HIGHMEM
machines, but this is good enough to fix the actual bug we're seeing.

Fixes: 8147c4c4 ("jbd2: use a folio in jbd2_journal_write_metadata_buffer()")
Reported-by: default avatarZorro Lang <zlang@kernel.org>
Signed-off-by: default avatarRitesh Harjani (IBM) <ritesh.list@gmail.com>
[converted to be more folio]
Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
parent f94cf220

fs/jbd2/commit.c

+6 −10
Original line number Diff line number Diff line
@@ -298,14 +298,12 @@ static int journal_finish_inode_data_buffers(journal_t *journal, 


static __u32 jbd2_checksum_data(__u32 crc32_sum, struct buffer_head *bh)

{

	struct page *page = bh->b_page;

	char *addr;

	__u32 checksum;



	addr = kmap_atomic(page);

	checksum = crc32_be(crc32_sum,

		(void *)(addr + offset_in_page(bh->b_data)), bh->b_size);

	kunmap_atomic(addr);

	addr = kmap_local_folio(bh->b_folio, bh_offset(bh));

	checksum = crc32_be(crc32_sum, addr, bh->b_size);

	kunmap_local(addr);



	return checksum;

}
@@ -322,7 +320,6 @@ static void jbd2_block_tag_csum_set(journal_t *j, journal_block_tag_t *tag, 
				    struct buffer_head *bh, __u32 sequence)

{

	journal_block_tag3_t *tag3 = (journal_block_tag3_t *)tag;

	struct page *page = bh->b_page;

	__u8 *addr;

	__u32 csum32;

	__be32 seq;
@@ -331,11 +328,10 @@ static void jbd2_block_tag_csum_set(journal_t *j, journal_block_tag_t *tag, 
		return;



	seq = cpu_to_be32(sequence);

	addr = kmap_atomic(page);

	addr = kmap_local_folio(bh->b_folio, bh_offset(bh));

	csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&seq, sizeof(seq));

	csum32 = jbd2_chksum(j, csum32, addr + offset_in_page(bh->b_data),

			     bh->b_size);

	kunmap_atomic(addr);

	csum32 = jbd2_chksum(j, csum32, addr, bh->b_size);

	kunmap_local(addr);



	if (jbd2_has_feature_csum3(j))

		tag3->t_checksum = cpu_to_be32(csum32);

fs/jbd2/transaction.c

+4 −8
Original line number Diff line number Diff line
@@ -935,19 +935,15 @@ static void warn_dirty_buffer(struct buffer_head *bh) 
/* Call t_frozen trigger and copy buffer data into jh->b_frozen_data. */

static void jbd2_freeze_jh_data(struct journal_head *jh)

{

	struct page *page;

	int offset;

	char *source;

	struct buffer_head *bh = jh2bh(jh);



	J_EXPECT_JH(jh, buffer_uptodate(bh), "Possible IO failure.\n");

	page = bh->b_page;

	offset = offset_in_page(bh->b_data);

	source = kmap_atomic(page);

	source = kmap_local_folio(bh->b_folio, bh_offset(bh));

	/* Fire data frozen trigger just before we copy the data */

	jbd2_buffer_frozen_trigger(jh, source + offset, jh->b_triggers);

	memcpy(jh->b_frozen_data, source + offset, bh->b_size);

	kunmap_atomic(source);

	jbd2_buffer_frozen_trigger(jh, source, jh->b_triggers);

	memcpy(jh->b_frozen_data, source, bh->b_size);

	kunmap_local(source);



	/*

	 * Now that the frozen data is saved off, we need to store any matching