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mm: add folio_fill_tail() and use it in iomap

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The iomap code was limited to PAGE_SIZE bytes; generalise it to cover
an arbitrary-sized folio, and move it to be a common helper.

[akpm@linux-foundation.org: fix folio_fill_tail(), per Andreas Gruenbacher]
Link: https://lkml.kernel.org/r/20231107212643.3490372-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2023-11-07 21:26:41 +00:00 committed by Andrew Morton
parent a4fc4a0c45
commit 6eaa266b54
2 changed files with 40 additions and 12 deletions
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14
fs/iomap/buffered-io.c
View File

@ -305,28 +305,18 @@ static int iomap_read_inline_data(const struct iomap_iter *iter,
{
const struct iomap *iomap = iomap_iter_srcmap(iter);
size_t size = i_size_read(iter->inode) - iomap->offset;
size_t poff = offset_in_page(iomap->offset);
size_t offset = offset_in_folio(folio, iomap->offset);
void *addr;
if (folio_test_uptodate(folio))
return 0;
if (WARN_ON_ONCE(size > PAGE_SIZE - poff))
return -EIO;
if (WARN_ON_ONCE(size > PAGE_SIZE -
offset_in_page(iomap->inline_data)))
return -EIO;
if (WARN_ON_ONCE(size > iomap->length))
return -EIO;
if (offset > 0)
ifs_alloc(iter->inode, folio, iter->flags);
addr = kmap_local_folio(folio, offset);
memcpy(addr, iomap->inline_data, size);
memset(addr + size, 0, PAGE_SIZE - poff - size);
kunmap_local(addr);
iomap_set_range_uptodate(folio, offset, PAGE_SIZE - poff);
folio_fill_tail(folio, offset, iomap->inline_data, size);
iomap_set_range_uptodate(folio, offset, folio_size(folio) - offset);
return 0;
}

38
include/linux/highmem.h
View File

@ -521,6 +521,44 @@ static inline __must_check void *folio_zero_tail(struct folio *folio,
return kaddr;
}
/**
* folio_fill_tail - Copy some data to a folio and pad with zeroes.
* @folio: The destination folio.
* @offset: The offset into @folio at which to start copying.
* @from: The data to copy.
* @len: How many bytes of data to copy.
*
* This function is most useful for filesystems which support inline data.
* When they want to copy data from the inode into the page cache, this
* function does everything for them. It supports large folios even on
* HIGHMEM configurations.
*/
static inline void folio_fill_tail(struct folio *folio, size_t offset,
const char *from, size_t len)
{
char *to = kmap_local_folio(folio, offset);
VM_BUG_ON(offset + len > folio_size(folio));
if (folio_test_highmem(folio)) {
size_t max = PAGE_SIZE - offset_in_page(offset);
while (len > max) {
memcpy(to, from, max);
kunmap_local(to);
len -= max;
from += max;
offset += max;
max = PAGE_SIZE;
to = kmap_local_folio(folio, offset);
}
}
memcpy(to, from, len);
to = folio_zero_tail(folio, offset + len, to + len);
kunmap_local(to);
}
/**
* memcpy_from_file_folio - Copy some bytes from a file folio.
* @to: The destination buffer.