-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Mon, 29 Apr 2013 07:33:21 +0200 Harald Hoyer <harald@xxxxxxxxxx> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On 04/29/2013 02:57 AM, NeilBrown wrote: > > On Thu, 11 Apr 2013 15:18:33 +0200 Jes.Sorensen@xxxxxxxxxx wrote: > > > >> From: Harald Hoyer <harald@xxxxxxxxxx> > >> > >> This does not trigger the udev inotify twice and saves a lot of blk I/O > >> for the raid members. > >> > >> Also fixes: https://bugzilla.redhat.com/show_bug.cgi?id=947815 > >> > >> Signed-off-by: Harald Hoyer <harald@xxxxxxxxxx> Signed-off-by: Jes > >> Sorensen <Jes.Sorensen@xxxxxxxxxx> > > > > (Sorry for delays. Thanks for reminders). > > > > That patch seems to make sense, but the description above is awfully thin. > > > > Why is double-open a problem exactly? What does it make udev do? And how > > does that related to ID_FS_TYPE being wrong as mentioned in the bugzilla > > entry. > > > > NeilBrown > > > > udevd with watch enabled (inotify on /dev/sd*) gets triggered on close(), when > you opened it writeable. So, if you double open() and udev wakes up from the > first close(), not all information are written to disk yet, it will not get > the ID_FS_TYPE. > > Seems like the second close() does not trigger an inotify sometimes, so it is > missing afterwards all the time. > > Watch via inotify is just a lazy workaround, so we don't have to modify every > tool to emit a "change" uevent, after they changed the disk. So udev have a "lazy workaround" so that other programs don't need to trigger a change, and as a result, I need to add some special code to mdadm. Doesn't seem like I'm getting any advantage out of this laziness. How about when udev gets an inotify for a block device, it first checks that it can open it O_EXCL. If not, it doesn't generate the change event. That seems like the laziest option to me :-) NeilBrown > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.13 (GNU/Linux) > Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ > > iQIcBAEBAgAGBQJRfgYhAAoJEANOs3ABTfJw0uUQALrm0pEjlLd6XgojMTQ6xJGy > y98MVcobi10O/WJyg3HV1RqjnYNu7wfpp+lFIzKRmE/sxIBj8X9ATFfjaopCGWYC > /MPGsdehrCpGPPOZBlt47vTdoaKWB5meKsBm3X1I0AhA+uOxgeV2qfaijoOkHeim > a4RbIUoOJIjIyvbdKCuVbs8mqcr62eMUiZBDPv/b3FcBtOOjYkWVZU14ylqujNtM > WzE+soKyd6L70DvPWVY2KzJ4/5bg/fRuvFcc464k88hAqa8U36FU6MzfTuT4K+ZH > a4FYJtpdrggL+IZuG5XToNR5lpR/YW/B1UBhfCjItXbr1dhX3alk+Y3xZCWvpbRF > FFwAA1GJfcB8UmKp3loBX0YH4gJ8h8d6EITE0Quj38VqG4MlCl89J6ClQZYgXsf8 > ZCVDX+lomiQkEp5xYyC85hmwfwepibncqfqKef8+4ABc5xWswQr89gDFPVsFZUE/ > PbHzCUlAkz8lvuRSNH6k54b7nFeGn116eJgO7sKESt4uygP0o1A6WpWZI+YAMMg5 > CBkxrLYM/iERP7sf8kHr3Wd5EWJNTYm6UsJjVtWStGHuB7LNDo6qPBXxzf84Mkek > 1fnIqBfl6QDQBcYb+02p2vGhcTA+P/byi+j+eFQmwV8g2gbkwxhV6/t0Sizj57tC > SlUZAaWHeeNK9HDgoNJ0 > =zkJO > -----END PGP SIGNATURE----- -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) iQIVAwUBUX4PDDnsnt1WYoG5AQInKA/+PyFlr+sO0cHRQRxG6EMi1Uy649MAf1u+ TOnvspRNilHs+ackxKOyT3ZNHYUwyeybVKlAvKuZ8ynObtUmE+E7OnGOcqLl28Ml As92W35y56qPl1czDhX/UDAZALjI0FrHcDBJLxef8bWLXCsEoUpPeqF5ddfmsvzL 7XR9Aiy7LHkBXQbPciYneR1kZHnuNF3zBFtt68bAnK4hV4128LuohM3v6FM4CU5q fiZpo+gqeKdnu7oev0Xh6inaP5MfupGvYA9UTTPiRV/Rg+9tv2Y/hSHtYE/mvWbH lLLAHq1e7Pcu1wCwXmlW0h2ph5rcs3rBOgQYpFWet65nbFk76q+NY01m0tqelVbv 6wt1JVyUxopHMy9FLypg+/cctDYLimgDFd2eG5B2YXL/lF5EBclM3PmhMDR6ITun wWGhburperRwKYVZszv9Eo8Teu1ed/1gDnD69XlOa8dOOXtj95WcBDGz6p+1hM/Q H7bWwXEiXreMrv3WtCvoghakM+ul9P3vZXo83Vwv7x7WDteEQ6ZYUe9CdVuM/k3r x+CYz7kjfkg2oZEZmN11pe3UoU+eCBR3FOm1xvbEiQt5SWZm8mRd7v7Y2qVI3e3C Q9M5rEJ8wws20JrRXHEtkOCX1FzeiYOi5calDWUzf+2AyY86NYv214SM98qWXgju AyUaIO7u0Mg= =zg9i -----END PGP SIGNATURE----- ÿôèº{.nÇ+?·?®??+%?Ëÿ±éݶ¥?wÿº{.nÇ+?·¥?{±þ¶¢wø§¶?¡Ü¨}©?²Æ zÚ&j:+v?¨þø ¯ù ®w¥þ?à2?Þ?¨èÚ&¢)ß¡«a¶Úÿÿûàz¿äz¹Þ?ú+?ù???Ý¢jÿ?wèþf
