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| author | David Teigland <teigland@redhat.com> | 2020-09-18 14:42:23 -0500 |
|---|---|---|
| committer | David Teigland <teigland@redhat.com> | 2020-09-18 15:10:11 -0500 |
| commit | 1404e5ee61bdaddeb07a5e9ecfe1aad477cc9bf9 (patch) | |
| tree | c923e58968ba40073e79724f0dd5a92988959e28 /lib/cache | |
| parent | 1570e76233398957911c3559b40de6e03c37df9a (diff) | |
| download | lvm2-1404e5ee61bdaddeb07a5e9ecfe1aad477cc9bf9.tar.gz | |
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
Diffstat (limited to 'lib/cache')
| -rw-r--r-- | lib/cache/lvmcache.c | 16 | ||||
| -rw-r--r-- | lib/cache/lvmcache.h | 1 |
2 files changed, 17 insertions, 0 deletions
diff --git a/lib/cache/lvmcache.c b/lib/cache/lvmcache.c index cad8247c7..d8df4c796 100644 --- a/lib/cache/lvmcache.c +++ b/lib/cache/lvmcache.c @@ -996,6 +996,22 @@ int lvmcache_label_rescan_vg_rw(struct cmd_context *cmd, const char *vgname, con return _label_rescan_vg(cmd, vgname, vgid, 1); } +int lvmcache_label_reopen_vg_rw(struct cmd_context *cmd, const char *vgname, const char *vgid) +{ + struct lvmcache_vginfo *vginfo; + struct lvmcache_info *info; + + if (!(vginfo = lvmcache_vginfo_from_vgname(vgname, vgid))) + return_0; + + dm_list_iterate_items(info, &vginfo->infos) { + if (!label_scan_reopen_rw(info->dev)) + return_0; + } + + return 1; +} + /* * Uses label_scan to populate lvmcache with 'vginfo' struct for each VG * and associated 'info' structs for those VGs. Only VG summary information diff --git a/lib/cache/lvmcache.h b/lib/cache/lvmcache.h index 6cef4d102..1ee99b534 100644 --- a/lib/cache/lvmcache.h +++ b/lib/cache/lvmcache.h @@ -69,6 +69,7 @@ void lvmcache_destroy(struct cmd_context *cmd, int retain_orphans, int reset); int lvmcache_label_scan(struct cmd_context *cmd); int lvmcache_label_rescan_vg(struct cmd_context *cmd, const char *vgname, const char *vgid); int lvmcache_label_rescan_vg_rw(struct cmd_context *cmd, const char *vgname, const char *vgid); +int lvmcache_label_reopen_vg_rw(struct cmd_context *cmd, const char *vgname, const char *vgid); /* Add/delete a device */ struct lvmcache_info *lvmcache_add(struct cmd_context *cmd, struct labeller *labeller, const char *pvid, |