btrfs-progs: udev: add rules for dm devices

Systemd's btrfs rule runs btrfs dev ready on each device
as it's discovered.  The btrfs command is executed as a builtin
command via an IMPORT{builtin} rule, which means it gets
executed at rule evaluation time, not rule execution time.  That
means that the device mapper links haven't been setup yet and the only
nodes that can be depended upon are /dev/dm-#.  That we see
/dev/mapper/name names in /proc/mounts is only because we replace the
device name we have cached with the one passed in via mount.  If
we have a multi-device file system and the primary device is removed,
the remaining devices will show /dev/dm-#.  In addition, if the
udev rule is executed again by someone generating a change event (e.g.
partprobe), the names are also replaced by the /dev/dm-# names.

This patch adds a new rule that adds a run rule that calls btrfs dev
ready again using the device mapper links once they're created.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
master
Jeff Mahoney 2016-05-09 11:44:26 -04:00 committed by David Sterba
parent 640391b299
commit 62c0666378
3 changed files with 20 additions and 0 deletions

10
64-btrfs-dm.rules 100644
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@ -0,0 +1,10 @@
SUBSYSTEM!="block", GOTO="btrfs_end"
KERNEL!="dm-[0-9]*", GOTO="btrfs_end"
ACTION!="add|change", GOTO="btrfs_end"
ENV{ID_FS_TYPE}!="btrfs", GOTO="btrfs_end"
# Once the device mapper symlink is created, tell btrfs about it
# so we get the friendly name in /proc/mounts (and tools that read it)
ENV{DM_NAME}=="?*", RUN{builtin}+="btrfs ready /dev/mapper/$env{DM_NAME}"
LABEL="btrfs_end"

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@ -84,11 +84,15 @@ libbtrfs_headers = send-stream.h send-utils.h send.h rbtree.h btrfs-list.h \
extent_io.h ioctl.h ctree.h btrfsck.h version.h
TESTS = fsck-tests.sh convert-tests.sh
udev_rules = 64-btrfs-dm.rules
prefix ?= @prefix@
exec_prefix = @exec_prefix@
bindir = @bindir@
libdir ?= @libdir@
incdir = @includedir@/btrfs
udevdir = @UDEVDIR@
udevruledir = ${udevdir}/rules.d
ifeq ("$(origin V)", "command line")
BUILD_VERBOSE = $(V)
@ -390,6 +394,10 @@ install: $(libs) $(progs_install) $(INSTALLDIRS)
cp -a $(lib_links) $(DESTDIR)$(libdir)
$(INSTALL) -m755 -d $(DESTDIR)$(incdir)
$(INSTALL) -m644 $(headers) $(DESTDIR)$(incdir)
ifneq ($(udevdir),)
$(INSTALL) -m755 -d $(DESTDIR)$(udevruledir)
$(INSTALL) -m644 $(udev_rules) $(DESTDIR)$(udevruledir)
endif
install-static: $(progs_static) $(INSTALLDIRS)
$(INSTALL) -m755 -d $(DESTDIR)$(bindir)

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@ -124,6 +124,8 @@ PKG_STATIC(UUID_LIBS_STATIC, [uuid])
PKG_CHECK_MODULES(ZLIB, [zlib])
PKG_STATIC(ZLIB_LIBS_STATIC, [zlib])
PKG_CHECK_VAR([UDEVDIR], [udev], [udevdir])
dnl lzo library does not provide pkg-config, let use classic way
AC_CHECK_LIB([lzo2], [lzo_version], [
LZO2_LIBS="-llzo2"