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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This archive was generated by hypermail 2b29 : Sun Jan 07 2001 - 21:00:17 EST