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shmem: minor fixes to splice-read implementation

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HWPoison: my reading of folio_test_hwpoison() is that it only tests the
head page of a large folio, whereas splice_folio_into_pipe() will splice
as much of the folio as it can: so for safety we should also check the
has_hwpoisoned flag, set if any of the folio's pages are hwpoisoned. 
(Perhaps that ugliness can be improved at the mm end later.)

The call to splice_zeropage_into_pipe() risked overrunning past EOF: ask
it for "part" not "len".

Link: https://lkml.kernel.org/r/32c72c9c-72a8-115f-407d-f0148f368@google.com
Fixes: bd194b1871 ("shmem: Implement splice-read")
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Hugh Dickins 2023-07-23 14:05:54 -07:00 committed by Andrew Morton
parent 253e5df8b8
commit fa598952fa
1 changed files with 6 additions and 3 deletions
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9
mm/shmem.c
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@ -2796,7 +2796,8 @@ static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
if (*ppos >= i_size_read(inode))
break;
error = shmem_get_folio(inode, *ppos / PAGE_SIZE, &folio, SGP_READ);
error = shmem_get_folio(inode, *ppos / PAGE_SIZE, &folio,
SGP_READ);
if (error) {
if (error == -EINVAL)
error = 0;
@ -2805,7 +2806,9 @@ static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
if (folio) {
folio_unlock(folio);
if (folio_test_hwpoison(folio)) {
if (folio_test_hwpoison(folio) ||
(folio_test_large(folio) &&
folio_test_has_hwpoisoned(folio))) {
error = -EIO;
break;
}
@ -2841,7 +2844,7 @@ static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
folio_put(folio);
folio = NULL;
} else {
n = splice_zeropage_into_pipe(pipe, *ppos, len);
n = splice_zeropage_into_pipe(pipe, *ppos, part);
}
if (!n)