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buffer: convert block_page_mkwrite() to use a folio

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If any page in a folio is dirtied, dirty the entire folio.  Removes a
number of hidden calls to compound_head() and references to page->mapping
and page->index.  Fixes a pre-existing bug where we could mark a folio as
dirty if the file is truncated to a multiple of the page size just as we
take the page fault.  I don't believe this bug has any bad effect, it's
just inefficient.

Link: https://lkml.kernel.org/r/20230612210141.730128-8-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Bob Peterson <rpeterso@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle)
2023-06-12 22:01:34 +01:00
committed by Andrew Morton
parent bb0ea5989c
commit fe181377a2
1 changed files with 13 additions and 14 deletions
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27
fs/buffer.c
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@@ -2564,38 +2564,37 @@ EXPORT_SYMBOL(block_commit_write);
int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
get_block_t get_block)
{
struct page *page = vmf->page;
struct folio *folio = page_folio(vmf->page);
struct inode *inode = file_inode(vma->vm_file);
unsigned long end;
loff_t size;
int ret;
lock_page(page);
folio_lock(folio);
size = i_size_read(inode);
if ((page->mapping != inode->i_mapping) ||
(page_offset(page) > size)) {
if ((folio->mapping != inode->i_mapping) ||
(folio_pos(folio) >= size)) {
/* We overload EFAULT to mean page got truncated */
ret = -EFAULT;
goto out_unlock;
}
/* page is wholly or partially inside EOF */
if (((page->index + 1) << PAGE_SHIFT) > size)
end = size & ~PAGE_MASK;
else
end = PAGE_SIZE;
end = folio_size(folio);
/* folio is wholly or partially inside EOF */
if (folio_pos(folio) + end > size)
end = size - folio_pos(folio);
ret = __block_write_begin(page, 0, end, get_block);
ret = __block_write_begin_int(folio, 0, end, get_block, NULL);
if (!ret)
ret = block_commit_write(page, 0, end);
ret = block_commit_write(&folio->page, 0, end);
if (unlikely(ret < 0))
goto out_unlock;
set_page_dirty(page);
wait_for_stable_page(page);
folio_mark_dirty(folio);
folio_wait_stable(folio);
return 0;
out_unlock:
unlock_page(page);
folio_unlock(folio);
return ret;
}
EXPORT_SYMBOL(block_page_mkwrite);