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iomap_dio_actor(): fix iov_iter bugs

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1) Ignoring return value from iov_iter_zero() is wrong
for iovec-backed case as well as for pipes - it can fail.

2) Failure to fault destination pages in 25Mb into a 50Mb iovec
should not act as if nothing in the area had been read, nevermind
that the first 25Mb might have *already* been read by that point.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2017-09-11 21:17:09 +01:00 committed by Al Viro
parent 8ececffa12
commit cfe057f7db
1 changed files with 15 additions and 9 deletions
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24
fs/iomap.c
View file

@ -848,6 +848,7 @@ iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
struct bio *bio;
bool need_zeroout = false;
int nr_pages, ret;
size_t copied = 0;
if ((pos | length | align) & ((1 << blkbits) - 1))
return -EINVAL;
@ -859,7 +860,7 @@ iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
/*FALLTHRU*/
case IOMAP_UNWRITTEN:
if (!(dio->flags & IOMAP_DIO_WRITE)) {
iov_iter_zero(length, dio->submit.iter);
length = iov_iter_zero(length, dio->submit.iter);
dio->size += length;
return length;
}
@ -896,8 +897,11 @@ iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
}
do {
if (dio->error)
size_t n;
if (dio->error) {
iov_iter_revert(dio->submit.iter, copied);
return 0;
}
bio = bio_alloc(GFP_KERNEL, nr_pages);
bio_set_dev(bio, iomap->bdev);
@ -910,20 +914,24 @@ iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
ret = bio_iov_iter_get_pages(bio, &iter);
if (unlikely(ret)) {
bio_put(bio);
return ret;
return copied ? copied : ret;
}
n = bio->bi_iter.bi_size;
if (dio->flags & IOMAP_DIO_WRITE) {
bio_set_op_attrs(bio, REQ_OP_WRITE, REQ_SYNC | REQ_IDLE);
task_io_account_write(bio->bi_iter.bi_size);
task_io_account_write(n);
} else {
bio_set_op_attrs(bio, REQ_OP_READ, 0);
if (dio->flags & IOMAP_DIO_DIRTY)
bio_set_pages_dirty(bio);
}
dio->size += bio->bi_iter.bi_size;
pos += bio->bi_iter.bi_size;
iov_iter_advance(dio->submit.iter, n);
dio->size += n;
pos += n;
copied += n;
nr_pages = iov_iter_npages(&iter, BIO_MAX_PAGES);
@ -939,9 +947,7 @@ iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
if (pad)
iomap_dio_zero(dio, iomap, pos, fs_block_size - pad);
}
iov_iter_advance(dio->submit.iter, length);
return length;
return copied;
}
ssize_t