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buffer: Make bh_offset() work for compound pages

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If the buffer pointed to by the buffer_head is part of a compound page,
bh_offset() assumes that b_page is the precise page that contains
the data.  A recent change to jbd2 inadvertently violated that assumption.

By using page_size(), we support both b_page being set to the head page
(as page_size() will return the size of the entire folio) and the precise
page (as it will return PAGE_SIZE for a tail page).

Fixes: 8147c4c4546f ("jbd2: use a folio in jbd2_journal_write_metadata_buffer()")
Reported-by: Zorro Lang <zlang@kernel.org>
Tested-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2023-09-07 09:40:07 -04:00 committed by Theodore Ts'o
parent 768d612f79
commit f94cf2206b
1 changed files with 4 additions and 1 deletions
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5
include/linux/buffer_head.h
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@ -173,7 +173,10 @@ static __always_inline int buffer_uptodate(const struct buffer_head *bh)
return test_bit_acquire(BH_Uptodate, &bh->b_state);
}
#define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
static inline unsigned long bh_offset(const struct buffer_head *bh)
{
return (unsigned long)(bh)->b_data & (page_size(bh->b_page) - 1);
}
/* If we *know* page->private refers to buffer_heads */
#define page_buffers(page) \