fuse: fix the ->direct_IO() treatment of iov_iter
[ Upstream commit 933a3752ba
]
the callers rely upon having any iov_iter_truncate() done inside
->direct_IO() countered by iov_iter_reexpand().
Reported-by: Qian Cai <cai@redhat.com>
Tested-by: Qian Cai <cai@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
parent
44b4baf850
commit
89fd103fbb
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@ -3074,11 +3074,10 @@ fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
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ssize_t ret = 0;
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struct file *file = iocb->ki_filp;
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struct fuse_file *ff = file->private_data;
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bool async_dio = ff->fc->async_dio;
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loff_t pos = 0;
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struct inode *inode;
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loff_t i_size;
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size_t count = iov_iter_count(iter);
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size_t count = iov_iter_count(iter), shortened = 0;
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loff_t offset = iocb->ki_pos;
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struct fuse_io_priv *io;
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@ -3086,17 +3085,9 @@ fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
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inode = file->f_mapping->host;
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i_size = i_size_read(inode);
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if ((iov_iter_rw(iter) == READ) && (offset > i_size))
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if ((iov_iter_rw(iter) == READ) && (offset >= i_size))
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return 0;
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/* optimization for short read */
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if (async_dio && iov_iter_rw(iter) != WRITE && offset + count > i_size) {
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if (offset >= i_size)
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return 0;
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iov_iter_truncate(iter, fuse_round_up(ff->fc, i_size - offset));
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count = iov_iter_count(iter);
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}
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io = kmalloc(sizeof(struct fuse_io_priv), GFP_KERNEL);
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if (!io)
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return -ENOMEM;
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@ -3112,15 +3103,22 @@ fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
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* By default, we want to optimize all I/Os with async request
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* submission to the client filesystem if supported.
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*/
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io->async = async_dio;
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io->async = ff->fc->async_dio;
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io->iocb = iocb;
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io->blocking = is_sync_kiocb(iocb);
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/* optimization for short read */
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if (io->async && !io->write && offset + count > i_size) {
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iov_iter_truncate(iter, fuse_round_up(ff->fc, i_size - offset));
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shortened = count - iov_iter_count(iter);
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count -= shortened;
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}
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/*
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* We cannot asynchronously extend the size of a file.
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* In such case the aio will behave exactly like sync io.
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*/
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if ((offset + count > i_size) && iov_iter_rw(iter) == WRITE)
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if ((offset + count > i_size) && io->write)
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io->blocking = true;
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if (io->async && io->blocking) {
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@ -3138,6 +3136,7 @@ fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
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} else {
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ret = __fuse_direct_read(io, iter, &pos);
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}
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iov_iter_reexpand(iter, iov_iter_count(iter) + shortened);
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if (io->async) {
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bool blocking = io->blocking;
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