6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: John Garry <john.g.garry@xxxxxxxxxx>
[ Upstream commit 2cbd51f1f8739fd2fdf4bae1386bcf75ce0176ba ]
A write which goes past the end of the bdev in blkdev_write_iter() will
be truncated. Truncating cannot tolerated for an atomic write, so error
that condition.
Fixes: caf336f81b3a ("block: Add fops atomic write support")
Signed-off-by: John Garry <john.g.garry@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Link: https://lore.kernel.org/r/20241127092318.632790-1-john.g.garry@xxxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
block/fops.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/block/fops.c b/block/fops.c
index 2d01c90076813..13a67940d0408 100644
--- a/block/fops.c
+++ b/block/fops.c
@@ -677,6 +677,7 @@ static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
struct file *file = iocb->ki_filp;
struct inode *bd_inode = bdev_file_inode(file);
struct block_device *bdev = I_BDEV(bd_inode);
+ bool atomic = iocb->ki_flags & IOCB_ATOMIC;
loff_t size = bdev_nr_bytes(bdev);
size_t shorted = 0;
ssize_t ret;
@@ -696,7 +697,7 @@ static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT)
return -EOPNOTSUPP;
- if (iocb->ki_flags & IOCB_ATOMIC) {
+ if (atomic) {
ret = generic_atomic_write_valid(iocb, from);
if (ret)
return ret;
@@ -704,6 +705,8 @@ static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
size -= iocb->ki_pos;
if (iov_iter_count(from) > size) {
+ if (atomic)
+ return -EINVAL;
shorted = iov_iter_count(from) - size;
iov_iter_truncate(from, size);
}
--
2.43.0
