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Commit Graph

19 Commits

Author SHA1 Message Date
Bryn M. Reeves
5e74e43896 dmfilemapd: cast return value of strto* functions when needed 2017-03-30 10:02:31 +01:00
Bryn M. Reeves
834574cc27 dmfilemapd: use log_sys_error in _filemap_monitor_set_notify
Since _filemap_monitor_set_notify() is only called after daemon
start up it should not use the _early_log() macros. Instead, use
log_sys_error to log errors from the two syscalls in the function.
2017-03-30 10:01:57 +01:00
Bryn M. Reeves
bfc880994c dmfilemapd: cast sysconf() return value to int 2017-03-30 09:57:58 +01:00
Bryn M. Reeves
76b6cbea60 dmfilemapd: fix len type in _filemap_monitor_check_file_unlinked()
Make 'len' a size_t to match the return type of readlink(2).
2017-03-30 09:57:58 +01:00
Bryn M. Reeves
660bd4fe3e dmfilemapd: make filemap_monitor->nr_regions uint64_t 2017-03-30 09:57:58 +01:00
Bryn M. Reeves
13426092e9 dmfilemapd: free region table at end of _update_regions() (coverity) 2017-03-29 18:34:24 +01:00
Bryn M. Reeves
f66bc3dab0 dmfilemapd: fix off-by-one in fd comparison (coverity)
The function _filemap_monitor_check_file_unlinked() attempts to
test whether a fd value should be closed by comparison to zero:

        if ((fd > 0) && close(fd))
                log_error("Error closing fd %d", fd);

The test should be '>=' since 0 is a valid file descriptor.
2017-03-29 18:34:19 +01:00
Bryn M. Reeves
8658bbe3ee dmfilemapd: always close link check file descriptor (coverity)
Similar to 40fb91a, but for the file descriptor opened using the
link path reported by /proc/<self>/fd/<fd>.

The daemon opens a new file descriptor from /proc/<self>/fd when
checking for an unlinked file with mode=inode. Ensure that it is
always closed even if the same file test fails.
2017-03-29 18:34:11 +01:00
Bryn M. Reeves
7db51a6bed dmfilemapd: always terminate link buffer after readlink(2) (coverity) 2017-03-29 18:34:05 +01:00
Bryn M. Reeves
70bb726678 dmfilemapd: always close check file descriptor (coverity)
The daemon opens a new file descriptor from fm->path when checking
for an unlinked file with mode=inode. Ensure that it is always
closed even if the same file test fails.
2017-03-29 18:33:53 +01:00
Bryn M. Reeves
43fdbb8aeb dmfilemapd: use *argv[0] when testing for absolute path (coverity)
The path argument check in dmfilemapd incorrectly tests for:

  if (argv[0] == '/')

Rather than testing the 1st character in the string pointed to by
argv[0].
2017-03-29 18:33:42 +01:00
Bryn M. Reeves
b5252a51a5 dmfilemapd: pass correct dirp to closedir() 2017-03-29 16:54:44 +01:00
Bryn M. Reeves
481a522dd7 dmfilemapd: do not closdir(pid_d) unless it is open 2017-03-29 16:48:32 +01:00
Bryn M. Reeves
d71071a1af dmfilemapd: log closedir errors with log_sys_error() 2017-03-29 16:04:15 +01:00
Bryn M. Reeves
77a7ed065f dmfilemapd: ensure path argument is absolute
Require that the path argument to dmfilemapd be an absolute path
and document this in tool output, libdevmapper.h and dmfilemapd.8.

The check is also enforced by dm_stats_start_filemapd() to avoid
forking a new process with an invalid path argument.
2017-03-13 11:44:05 +00:00
Bryn M. Reeves
9b0aba5fe9 dmfilemapd: return error for wrong number of args
The initial check on argc incorrectly returns 1 when the wrong
number of arguments are present, causing a segfault in main()
when no arguments are given:

  # dmfilemapd
  Wrong number of arguments.
  usage: dmfilemapd <fd> <group_id> <path> <mode> [<foreground>[<log_level>]]
  Segmentation fault (core dumped)
2017-03-13 11:09:11 +00:00
Bryn M. Reeves
a9341b18ef daemons: use DEFAULT_PROC_DIR in dmfilemapd
Include defaults.h and use it to obtain the default procfs mount
point in dmfilemapd.
2017-03-10 17:26:47 +00:00
Bryn M. Reeves
1ba11aa7ee dmfilemapd: always set the program_id after listing regions
The filemap daemon takes its program_id from the regions it is
managing: use DM_STATS_ALL_PROGRAMS when retrieving an initial
listing and then obtain the correct program_id from the group
leader.
2017-03-09 21:20:27 +00:00
Bryn M. Reeves
8b78982297 daemons: add dmfilemapd
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.
2017-03-09 18:50:15 +00:00