On Tue, Apr 04, 2017 at 12:25:46PM -0400, Jeff Layton wrote:
> That said, I think giving more specific errors where we can is useful.
> When your program is erroring out and writing 'I/O error' to the logs,
> then how much time will your admins burn before they figure out that it
> really failed because the filesystem was full?
df is one of the first things I check ... a few years ago, I also learned
to check df -i ... ;-)
Anyway, given the decision to simply report the last error lets us do this
implementation:
void filemap_set_wb_error(struct address_space *mapping, int err)
{
struct inode *inode = mapping->host;
unsigned int wb_err;
if (!err)
return;
/*
* This should be called with the error code that we want to return
* on fsync. Thus, it should always be <= 0.
*/
WARN_ON(err > 0 || err < -MAX_ERRNO);
spin_lock(&inode->i_lock);
wb_err = ((mapping->wb_err & ~MAX_ERRNO) + (1 << 12)) | -err;
WRITE_ONCE(mapping->wb_err, wb_err);
spin_unlock(&inode->i_lock);
}
int filemap_report_wb_error(struct file *file)
{
struct inode *inode = file_inode(file);
unsigned int wb_err = READ_ONCE(mapping->wb_err);
if (file->f_wb_err == wb_err)
return 0;
return -(wb_err & 4095);
}
That only gives us 20 bits of counter, but I think that's enough.
