diff options
Diffstat (limited to 'mm/filemap.c')
| -rw-r--r-- | mm/filemap.c | 36 |
1 files changed, 15 insertions, 21 deletions
diff --git a/mm/filemap.c b/mm/filemap.c index ac82a93d4f38..d1458ecf2f51 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -3642,10 +3642,6 @@ again: * Otherwise there's a nasty deadlock on copying from the * same page as we're writing to, without it being marked * up-to-date. - * - * Not only is this an optimisation, but it is also required - * to check that the address is actually valid, when atomic - * usercopies are used, below. */ if (unlikely(iov_iter_fault_in_readable(i, bytes))) { status = -EFAULT; @@ -3665,33 +3661,31 @@ again: if (mapping_writably_mapped(mapping)) flush_dcache_page(page); - copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes); + copied = copy_page_from_iter_atomic(page, offset, bytes, i); flush_dcache_page(page); status = a_ops->write_end(file, mapping, pos, bytes, copied, page, fsdata); - if (unlikely(status < 0)) - break; - copied = status; - + if (unlikely(status != copied)) { + iov_iter_revert(i, copied - max(status, 0L)); + if (unlikely(status < 0)) + break; + } cond_resched(); - iov_iter_advance(i, copied); - if (unlikely(copied == 0)) { + if (unlikely(status == 0)) { /* - * If we were unable to copy any data at all, we must - * fall back to a single segment length write. - * - * If we didn't fallback here, we could livelock - * because not all segments in the iov can be copied at - * once without a pagefault. + * A short copy made ->write_end() reject the + * thing entirely. Might be memory poisoning + * halfway through, might be a race with munmap, + * might be severe memory pressure. */ - bytes = min_t(unsigned long, PAGE_SIZE - offset, - iov_iter_single_seg_count(i)); + if (copied) + bytes = copied; goto again; } - pos += copied; - written += copied; + pos += status; + written += status; balance_dirty_pages_ratelimited(mapping); } while (iov_iter_count(i)); |