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btrfs: open-code btrfs_copy_from_user()

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The function btrfs_copy_from_user() handles the folio dirtying for
buffered write. The original design is to allow that function to handle
multiple folios, but since commit c87c299776 ("btrfs: make buffered
write to copy one page a time") there is no need to support multiple
folios.

So here open-code btrfs_copy_from_user() to
copy_folio_from_iter_atomic() and flush_dcache_folio() calls.

The short-copy check and revert are still kept as-is.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2024-11-07 14:35:07 +10:30 committed by David Sterba
parent 4eca32d8d9
commit e3d9a19756
1 changed files with 18 additions and 48 deletions
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66
fs/btrfs/file.c
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@ -38,52 +38,6 @@
#include "super.h"
#include "print-tree.h"
/*
* Helper to fault in page and copy. This should go away and be replaced with
* calls into generic code.
*/
static noinline int btrfs_copy_from_user(loff_t pos, size_t write_bytes,
struct folio *folio, struct iov_iter *i)
{
size_t copied = 0;
size_t total_copied = 0;
int offset = offset_in_page(pos);
while (write_bytes > 0) {
size_t count = min_t(size_t, PAGE_SIZE - offset, write_bytes);
/*
* Copy data from userspace to the current page
*/
copied = copy_folio_from_iter_atomic(folio, offset, count, i);
/* Flush processor's dcache for this page */
flush_dcache_folio(folio);
/*
* if we get a partial write, we can end up with
* partially up to date page. These add
* a lot of complexity, so make sure they don't
* happen by forcing this copy to be retried.
*
* The rest of the btrfs_file_write code will fall
* back to page at a time copies after we return 0.
*/
if (unlikely(copied < count)) {
if (!folio_test_uptodate(folio)) {
iov_iter_revert(i, copied);
copied = 0;
}
if (!copied)
break;
}
write_bytes -= copied;
total_copied += copied;
offset += copied;
}
return total_copied;
}
/*
* Unlock folio after btrfs_file_write() is done with it.
*/
@ -107,7 +61,7 @@ static void btrfs_drop_folio(struct btrfs_fs_info *fs_info, struct folio *folio,
}
/*
* After btrfs_copy_from_user(), update the following things for delalloc:
* After copy_folio_from_iter_atomic(), update the following things for delalloc:
* - Mark newly dirtied folio as DELALLOC in the io tree.
* Used to advise which range is to be written back.
* - Mark modified folio as Uptodate/Dirty and not needing COW fixup
@ -1269,7 +1223,23 @@ ssize_t btrfs_buffered_write(struct kiocb *iocb, struct iov_iter *i)
break;
}
copied = btrfs_copy_from_user(pos, write_bytes, folio, i);
copied = copy_folio_from_iter_atomic(folio,
offset_in_folio(folio, pos), write_bytes, i);
flush_dcache_folio(folio);
/*
* If we get a partial write, we can end up with partially
* uptodate page. Although if sector size < page size we can
* handle it, but if it's not sector aligned it can cause
* a lot of complexity, so make sure they don't happen by
* forcing retry this copy.
*/
if (unlikely(copied < write_bytes)) {
if (!folio_test_uptodate(folio)) {
iov_iter_revert(i, copied);
copied = 0;
}
}
num_sectors = BTRFS_BYTES_TO_BLKS(fs_info, reserve_bytes);
dirty_sectors = round_up(copied + sector_offset,