Messages in this thread | | | Date | Thu, 4 Dec 2008 04:14:50 +0000 | From | Al Viro <> | Subject | [RFC] cdrom weirdness |
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1) CDROM_LOCKDOOR sets a global variable (keeplocked) that affects all cdroms. Intentional?
2) cdrom_dvd_rw_close_write() call can be delayed indefinitely by keeping an ioctl-only (opened with O_NDELAY) descriptor.
3) open cdrom for data, have the door locked, keep fd opened. open it again for write, have the open fail and cleanup in cdrom_open() will happily unlock the door for you. I'd change that to "lock if we had no lockers, unlock on failure exit if we did lock", but there's an interesting comment: /* Something failed. Try to unlock the drive, because some drivers (notably ide-cd) lock the drive after every command. ... What the hell is that about? It's not "some drivers", AFAICT - it's been done explicitly in open_for_data(). Or is there something really driver-specific in it?
4) while we are at it, if you clear lockdoor via sysctl while something has cdrom opened - no unlock on close for you.
5) autoeject happens on the last close *IF* the last file happens to be opened for data. IOW, if some crap has opened it ioctl-only and kept that opened after everyone else has closed - no autoeject for you.
6) /* * flush cache on last write release */ if (CDROM_CAN(CDC_RAM) && !cdi->use_count && cdi->for_data) cdrom_close_write(cdi); is interesting, seeing that nothing has ever touched ->for_data, for values of "ever" including "since the code in question had been merged into the tree"...
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