Messages in this thread |  | | Date | Wed, 28 May 2003 19:58:42 +0200 | From | Rob van Nieuwkerk <> | Subject | 2.4 bug: fifo-write causes diskwrites to read-only fs ! |
| |
Hi all,
It turns out that Linux is updating inode timestamps of fifos (named pipes) that are written to while residing on a read-only filesystem. It is not only updating in-ram info, but it will issue *physical* writes to the read-only fs on the disk !
I use a CompactFlash in an embedded application with a read-only root-fs on it. There are several processes that communicate with each other via fifos. This bug in Linux causes frequent writes to my CF and will shorten it's lifetime enormously ..
I've posted a report on the "mysterious writes" before: ( http://www.ussg.iu.edu/hypermail/linux/kernel/0303.2/1753.html ) (incorrectly) linking it to a possible bug in O_SYNC. Nothing came out of it.
But now I've completely tracked down the bug (logging all diskaccesses and seeing it undoubtly write in disksectors containing time-stamp info of fifo's). Looking back it would have been easier to prove that something is wrong: the modified time-stamps survive power-cycles. This is not supposed to happen on a read-only fs.
I've tried reading the kernel source to find where the bug lives, But I'm not too familiar with it. Anyone out there who can pin it down ?
greetings, Rob van Nieuwkerk
Sysinfo: -------- - various 2.4 kernels including RH-2.4.20-13.9, but also straight 2.4(ac) ones. - CompactFlash (= IDE disk) - Geode GX1 CPU (i586 compatible) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
|  |