On Wed 04-10-23 16:24:30, Cyril Hrubis wrote: > Hi! > > > TODO: readahead() on /proc/self/maps seems to succeed is that to be > > > expected? > > > > Not sure. > > How does llseek() work on the same fd? > > Looks like we we can seek in that file as well, accordingly to man pages > we cannot seek in pipe, socket, and fifo, which seems to match the > reality. We can apparently seek in O_DIRECTORY fd as well, not sure if > that is even useful. Seeking on O_DIRECTORY fd is actually well defined by POSIX. You can store current file position you've got back from lseek and you are guaranteed to get back at the same position in the directory if you lseek to it (even if there was a change to the directory, although effects on changed directory entries is undefined). This is actually pretty tough to implement in contemporary filesystems with non-trivial directory structure but that is how POSIX defined it... Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
