[PATCH] fuse: ensure progress in read and write
In direct_io mode, send at least one page per reqest. Previously it was possible that reqests with zero data were sent, and hence the read/write didn't make any progress, resulting in an infinite (though interruptible) loop. Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -475,7 +475,7 @@ static int fuse_get_user_pages(struct fuse_req *req, const char __user *buf,
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nbytes = min(nbytes, (unsigned) FUSE_MAX_PAGES_PER_REQ << PAGE_SHIFT);
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npages = (nbytes + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
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npages = min(npages, FUSE_MAX_PAGES_PER_REQ);
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npages = min(max(npages, 1), FUSE_MAX_PAGES_PER_REQ);
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down_read(¤t->mm->mmap_sem);
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npages = get_user_pages(current, current->mm, user_addr, npages, write,
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0, req->pages, NULL);
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@ -506,7 +506,6 @@ static ssize_t fuse_direct_io(struct file *file, const char __user *buf,
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return -EINTR;
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while (count) {
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size_t tmp;
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size_t nres;
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size_t nbytes = min(count, nmax);
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int err = fuse_get_user_pages(req, buf, nbytes, !write);
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@ -514,8 +513,8 @@ static ssize_t fuse_direct_io(struct file *file, const char __user *buf,
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res = err;
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break;
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}
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tmp = (req->num_pages << PAGE_SHIFT) - req->page_offset;
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nbytes = min(nbytes, tmp);
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nbytes = (req->num_pages << PAGE_SHIFT) - req->page_offset;
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nbytes = min(count, nbytes);
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if (write)
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nres = fuse_send_write(req, file, inode, pos, nbytes);
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else
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