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8b78982297
Add a daemon that can be launched to monitor a group of regions
corresponding to the extents of a file, and to update the regions as the
file's allocation changes.
The daemon is intended to be started from a library interface, but can
also be run from the command line:
dmfilemapd <fd> <group_id> <path> <mode> [<foreground>[<log_level>]]
Where fd is a file descriptor open on the mapped file, group_id is the
group identifier of the mapped group and mode is either "inode" or
"path". E.g.:
# dmfilemapd 3 0 vm.img inode 1 3 3<vm.img
...
If foreground is non-zero, the daemon will not fork to run in the
background. If verbose is non-zero, libdm and daemon log messages will
be printed.
It is possible for the group identifier to change when regions are
re-mapped: this occurs when the group leader is deleted (regroup=1 in
dm_stats_update_regions_from_fd()), and another region is created before
the daemon has a chance to recreate the leader region.
The operation is inherently racey since there is currently no way to
atomically move or resize a dm_stats region while retaining its
region_id.
Detect this condition and update the group_id value stored in the
filemap monitor.
A function is also provided in the the stats API to launch the filemap
monitoring daemon:
int dm_stats_start_filemapd(int fd, uint64_t group_id, const char *path,
dm_filemapd_mode_t mode, unsigned foreground,
unsigned verbose);
This carries out the first fork and execs dmfilemapd with the arguments
specified.
A dm_filemapd_mode_t value is specified by the mode argument: either
DM_FILEMAPD_FOLLOW_INODE, or DM_FILEMAPD_FOLLOW_PATH. A helper function,
dm_filemapd_mode_from_string(), is provided to parse a string containing
a valid mode name into the appropriate dm_filemapd_mode_t value.
70 lines
2.0 KiB
Makefile
70 lines
2.0 KiB
Makefile
#
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# Copyright (C) 2016 Red Hat, Inc. All rights reserved.
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#
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# This file is part of the device-mapper userspace tools.
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#
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# This copyrighted material is made available to anyone wishing to use,
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# modify, copy, or redistribute it subject to the terms and conditions
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# of the GNU Lesser General Public License v.2.1.
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#
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# You should have received a copy of the GNU Lesser General Public License
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# along with this program; if not, write to the Free Software Foundation,
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# Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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srcdir = @srcdir@
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top_srcdir = @top_srcdir@
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top_builddir = @top_builddir@
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SOURCES = dmfilemapd.c
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TARGETS = dmfilemapd
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.PHONY: install_dmeventd install_dmeventd_static
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INSTALL_DMFILEMAPD_TARGETS = install_dmfilemapd_dynamic
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CLEAN_TARGETS = dmfilemapd.static
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CFLOW_LIST = $(SOURCES)
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CFLOW_LIST_TARGET = $(LIB_NAME).cflow
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CFLOW_TARGET = dmfilemapd
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include $(top_builddir)/make.tmpl
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all: device-mapper
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device-mapper: $(TARGETS)
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LIBS += -ldevmapper
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LVMLIBS += -ldevmapper-event $(PTHREAD_LIBS)
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CFLAGS_dmeventd.o += $(EXTRA_EXEC_CFLAGS)
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dmfilemapd: $(LIB_SHARED) dmfilemapd.o
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$(CC) $(CFLAGS) $(LDFLAGS) $(EXTRA_EXEC_LDFLAGS) $(ELDFLAGS) -L. -o $@ dmfilemapd.o \
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$(DL_LIBS) $(LVMLIBS) $(LIBS) -rdynamic
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dmfilemapd.static: $(LIB_STATIC) dmfilemapd.o $(interfacebuilddir)/libdevmapper.a
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$(CC) $(CFLAGS) $(LDFLAGS) $(ELDFLAGS) -static -L. -L$(interfacebuilddir) -o $@ \
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dmfilemapd.o $(DL_LIBS) $(LVMLIBS) $(LIBS) $(STATIC_LIBS)
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ifneq ("$(CFLOW_CMD)", "")
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CFLOW_SOURCES = $(addprefix $(srcdir)/, $(SOURCES))
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-include $(top_builddir)/libdm/libdevmapper.cflow
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-include $(top_builddir)/lib/liblvm-internal.cflow
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-include $(top_builddir)/lib/liblvm2cmd.cflow
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-include $(top_builddir)/daemons/dmfilemapd/$(LIB_NAME).cflow
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endif
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install_dmfilemapd_dynamic: dmfilemapd
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$(INSTALL_PROGRAM) -D $< $(sbindir)/$(<F)
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install_dmfilemapd_static: dmfilemapd.static
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$(INSTALL_PROGRAM) -D $< $(staticdir)/$(<F)
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install_dmfilemapd: $(INSTALL_DMEVENTD_TARGETS)
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install: install_dmfilemapd
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install_device-mapper: install_dmfilemapd
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