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block: Don't allow an atomic write be truncated in blkdev_write_iter()

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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: caf336f81b ("block: Add fops atomic write support")
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20241127092318.632790-1-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
John Garry 2024-11-27 09:23:18 +00:00 committed by Jens Axboe
parent 1b0cab327e
commit 2cbd51f1f8
1 changed files with 4 additions and 1 deletions
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5
block/fops.c
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@ -677,6 +677,7 @@ static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
struct file *file = iocb->ki_filp; struct file *file = iocb->ki_filp;
struct inode *bd_inode = bdev_file_inode(file); struct inode *bd_inode = bdev_file_inode(file);
struct block_device *bdev = I_BDEV(bd_inode); struct block_device *bdev = I_BDEV(bd_inode);
bool atomic = iocb->ki_flags & IOCB_ATOMIC;
loff_t size = bdev_nr_bytes(bdev); loff_t size = bdev_nr_bytes(bdev);
size_t shorted = 0; size_t shorted = 0;
ssize_t ret; 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) if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT)
return -EOPNOTSUPP; return -EOPNOTSUPP;
if (iocb->ki_flags & IOCB_ATOMIC) { if (atomic) {
ret = generic_atomic_write_valid(iocb, from); ret = generic_atomic_write_valid(iocb, from);
if (ret) if (ret)
return ret; return ret;
@ -704,6 +705,8 @@ static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
size -= iocb->ki_pos; size -= iocb->ki_pos;
if (iov_iter_count(from) > size) { if (iov_iter_count(from) > size) {
if (atomic)
return -EINVAL;
shorted = iov_iter_count(from) - size; shorted = iov_iter_count(from) - size;
iov_iter_truncate(from, size); iov_iter_truncate(from, size);
} }