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Fixes for 6.6-rc3:

Browse Source 
* Return EIO on bad inputs to iomap_to_bh instead of BUGging, to deal
   less poorly with block device io racing with block device resizing.
 * Fix a stale page data exposure bug introduced in 6.6-rc1 when
   unsharing a file range that is not in the page cache.
 
 Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Merge tag 'iomap-6.6-fixes-2' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux

Pull iomap fixes from Darrick Wong:

 - Return EIO on bad inputs to iomap_to_bh instead of BUGging, to deal
   less poorly with block device io racing with block device resizing

 - Fix a stale page data exposure bug introduced in 6.6-rc1 when
   unsharing a file range that is not in the page cache

* tag 'iomap-6.6-fixes-2' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  iomap: convert iomap_unshare_iter to use large folios
  iomap: don't skip reading in !uptodate folios when unsharing a range
  iomap: handle error conditions more gracefully in iomap_to_bh
This commit is contained in:
Linus Torvalds 2023-09-23 09:56:40 -07:00
commit 59c376d636
2 changed files with 32 additions and 23 deletions
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25
fs/buffer.c
View File

@ -2011,7 +2011,7 @@ void folio_zero_new_buffers(struct folio *folio, size_t from, size_t to)
}
EXPORT_SYMBOL(folio_zero_new_buffers);
static void
static int
iomap_to_bh(struct inode *inode, sector_t block, struct buffer_head *bh,
const struct iomap *iomap)
{
@ -2025,7 +2025,8 @@ iomap_to_bh(struct inode *inode, sector_t block, struct buffer_head *bh,
* current block, then do not map the buffer and let the caller
* handle it.
*/
BUG_ON(offset >= iomap->offset + iomap->length);
if (offset >= iomap->offset + iomap->length)
return -EIO;
switch (iomap->type) {
case IOMAP_HOLE:
@ -2037,7 +2038,7 @@ iomap_to_bh(struct inode *inode, sector_t block, struct buffer_head *bh,
if (!buffer_uptodate(bh) ||
(offset >= i_size_read(inode)))
set_buffer_new(bh);
break;
return 0;
case IOMAP_DELALLOC:
if (!buffer_uptodate(bh) ||
(offset >= i_size_read(inode)))
@ -2045,7 +2046,7 @@ iomap_to_bh(struct inode *inode, sector_t block, struct buffer_head *bh,
set_buffer_uptodate(bh);
set_buffer_mapped(bh);
set_buffer_delay(bh);
break;
return 0;
case IOMAP_UNWRITTEN:
/*
* For unwritten regions, we always need to ensure that regions
@ -2062,7 +2063,10 @@ iomap_to_bh(struct inode *inode, sector_t block, struct buffer_head *bh,
bh->b_blocknr = (iomap->addr + offset - iomap->offset) >>
inode->i_blkbits;
set_buffer_mapped(bh);
break;
return 0;
default:
WARN_ON_ONCE(1);
return -EIO;
}
}
@ -2103,13 +2107,12 @@ int __block_write_begin_int(struct folio *folio, loff_t pos, unsigned len,
clear_buffer_new(bh);
if (!buffer_mapped(bh)) {
WARN_ON(bh->b_size != blocksize);
if (get_block) {
if (get_block)
err = get_block(inode, block, bh, 1);
if (err)
break;
} else {
iomap_to_bh(inode, block, bh, iomap);
}
else
err = iomap_to_bh(inode, block, bh, iomap);
if (err)
break;
if (buffer_new(bh)) {
clean_bdev_bh_alias(bh);

30
fs/iomap/buffered-io.c
View File

@ -640,11 +640,13 @@ static int __iomap_write_begin(const struct iomap_iter *iter, loff_t pos,
size_t poff, plen;
/*
* If the write completely overlaps the current folio, then
* If the write or zeroing completely overlaps the current folio, then
* entire folio will be dirtied so there is no need for
* per-block state tracking structures to be attached to this folio.
* For the unshare case, we must read in the ondisk contents because we
* are not changing pagecache contents.
*/
if (pos <= folio_pos(folio) &&
if (!(iter->flags & IOMAP_UNSHARE) && pos <= folio_pos(folio) &&
pos + len >= folio_pos(folio) + folio_size(folio))
return 0;
@ -1261,7 +1263,6 @@ static loff_t iomap_unshare_iter(struct iomap_iter *iter)
const struct iomap *srcmap = iomap_iter_srcmap(iter);
loff_t pos = iter->pos;
loff_t length = iomap_length(iter);
long status = 0;
loff_t written = 0;
/* don't bother with blocks that are not shared to start with */
@ -1272,28 +1273,33 @@ static loff_t iomap_unshare_iter(struct iomap_iter *iter)
return length;
do {
unsigned long offset = offset_in_page(pos);
unsigned long bytes = min_t(loff_t, PAGE_SIZE - offset, length);
struct folio *folio;
int status;
size_t offset;
size_t bytes = min_t(u64, SIZE_MAX, length);
status = iomap_write_begin(iter, pos, bytes, &folio);
if (unlikely(status))
return status;
if (iter->iomap.flags & IOMAP_F_STALE)
if (iomap->flags & IOMAP_F_STALE)
break;
status = iomap_write_end(iter, pos, bytes, bytes, folio);
if (WARN_ON_ONCE(status == 0))
offset = offset_in_folio(folio, pos);
if (bytes > folio_size(folio) - offset)
bytes = folio_size(folio) - offset;
bytes = iomap_write_end(iter, pos, bytes, bytes, folio);
if (WARN_ON_ONCE(bytes == 0))
return -EIO;
cond_resched();
pos += status;
written += status;
length -= status;
pos += bytes;
written += bytes;
length -= bytes;
balance_dirty_pages_ratelimited(iter->inode->i_mapping);
} while (length);
} while (length > 0);
return written;
}