Messages in this thread | | | Date | Wed, 3 Jan 2001 21:29:48 -0800 (PST) | From | Asang K Dani <> | Subject | generic_file_write code segment in 2.2.18 |
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hi everyone, I was trying to understand following piece of code in 'generic_file_read' (mm/filemap.c) for 2.2.18 kernel. The code segment is as follows:
---------------------------------------------------------------- dest = (char *) page_address(page) + offset; if (dest != buf) { /* See comment in update_vm_cache_cond. */ bytes -= copy_from_user(dest, buf, bytes); flush_dcache_page(page_address(page)); } status = -EFAULT; if (bytes) status = inode->i_op->updatepage(file, page, offset, bytes, sync);
unlock: /* Mark it unlocked again and drop the page.. */ clear_bit(PG_locked, &page->flags); wake_up(&page->wait); page_cache_release(page);
if (status < 0) break;
written += status; count -= status; pos += status; buf += status; ---------------------------------------------------------------- copy_from_user returns the number of bytes copied from userspace to 'dest'. In case it succeeds, 'bytes' will be set to 0 after the call. However, 'status' is set to -EFAULT. So wouldn't it break out of the while loop (prematurely)?
Please post/CC your comments to me if this is not of general interest to the list and is too silly to be answered there.
regards, Asang Dani
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