David Teigland 1404e5ee61 metadata: open rw fd before closing ro fd ... lvm opens devices readonly to scan them, but needs to open then readwrite to update the metadata. Previously, the ro fd was closed before the rw fd was opened, leaving a small gap where the dev was not held open, and during which the dev could possibly change which storage it referred to. With the bcache_change_fd() interface, lvm opens a rw fd on a device to be written, tells bcache to change to the new rw fd, and closes the ro fd. . open dev ro . read dev with the ro fd (label_scan) . lock vg (ex for writing) . open dev rw . close ro fd . rescan dev to check if the metadata changed between the scan and the lock . if the metadata did change, reread in full . write the metadata		2020-09-18 15:10:11 -05:00
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lvmcache.c	metadata: open rw fd before closing ro fd	2020-09-18 15:10:11 -05:00
lvmcache.h	metadata: open rw fd before closing ro fd	2020-09-18 15:10:11 -05:00