mirror of
https://github.com/torvalds/linux
synced 2024-09-06 18:01:05 +00:00
generic_perform_write()/iomap_write_actor(): saner logics for short copy
if we run into a short copy and ->write_end() refuses to advance at all, use the amount we'd managed to copy for the next iteration to handle. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
parent
9067931236
commit
bc1bb416bb
|
@ -771,10 +771,6 @@ iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
|
|||
* 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;
|
||||
|
@ -791,25 +787,24 @@ iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
|
|||
|
||||
copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
|
||||
|
||||
copied = iomap_write_end(inode, pos, bytes, copied, page, iomap,
|
||||
status = iomap_write_end(inode, pos, bytes, copied, page, iomap,
|
||||
srcmap);
|
||||
|
||||
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 iomap_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;
|
||||
}
|
||||
copied = status;
|
||||
iov_iter_advance(i, copied);
|
||||
pos += copied;
|
||||
written += copied;
|
||||
length -= copied;
|
||||
|
|
24
mm/filemap.c
24
mm/filemap.c
|
@ -3642,10 +3642,6 @@ ssize_t generic_perform_write(struct file *file,
|
|||
* 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;
|
||||
|
@ -3672,24 +3668,22 @@ ssize_t generic_perform_write(struct file *file,
|
|||
page, fsdata);
|
||||
if (unlikely(status < 0))
|
||||
break;
|
||||
copied = status;
|
||||
|
||||
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;
|
||||
}
|
||||
copied = status;
|
||||
iov_iter_advance(i, copied);
|
||||
pos += copied;
|
||||
written += copied;
|
||||
|
||||
|
|
Loading…
Reference in a new issue