Hi, a POC patch to compress coredumps after they are written. In my simple tests, this brings huge savings, because the compressed coredump can compress to ~5%.
Unfortunately the core is first written uncompressed, then compressed by reading from disk and writing to the output file. This is ugly and slow, but I don't see a way around, if we want to get the backtrace without keeping everything in memory. 'coredumpctl gdb' is not implemented yet (the decompression part is missing). Thoughts, comments? Zbyszek --- src/journal/coredump.c | 125 ++++++++++++++++++++++++++++++++++++------------- 1 file changed, 92 insertions(+), 33 deletions(-) diff --git a/src/journal/coredump.c b/src/journal/coredump.c index 390f9598..97ee652c 100644 --- a/src/journal/coredump.c +++ b/src/journal/coredump.c @@ -41,6 +41,7 @@ #include "copy.h" #include "stacktrace.h" #include "path-util.h" +#include "compress.h" #ifdef HAVE_ACL #include <sys/acl.h> @@ -195,6 +196,47 @@ static int fix_xattr(int fd, const char *info[_INFO_LEN]) { #define filename_escape(s) xescape((s), "./ ") +static int fix_permissions(int fd, const char *filename, const char *target, + const char *info[_INFO_LEN], uid_t uid) { + + /* Ignore errors on these */ + fchmod(fd, 0640); + fix_acl(fd, uid); + fix_xattr(fd, info); + + if (fsync(fd) < 0) { + log_error("Failed to sync coredump %s: %m", filename); + return -errno; + } + + if (rename(filename, target) < 0) { + log_error("Failed to rename coredump %s -> %s: %m", filename, target); + return -errno; + } + + return 0; +} + +static int maybe_remove_external_coredump(const char *filename, off_t size) { + + /* Returns 1 if might remove, 0 if will not remove, <0 on error. */ + + if (IN_SET(arg_storage, COREDUMP_STORAGE_EXTERNAL, COREDUMP_STORAGE_BOTH) && + size <= arg_external_size_max) + return 0; + + if (!filename) + return 1; + + if (unlink(filename) < 0) { + log_error("Failed to unlink %s: %m", filename); + return -errno; + } + + return 1; +} + + static int save_external_coredump(const char *info[_INFO_LEN], uid_t uid, char **ret_filename, @@ -247,7 +289,7 @@ static int save_external_coredump(const char *info[_INFO_LEN], fd = open(tmp, O_CREAT|O_EXCL|O_RDWR|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW, 0640); if (fd < 0) { - log_error("Failed to create coredump file: %m"); + log_error("Failed to create coredump file %s: %m", tmp); return -errno; } @@ -265,29 +307,63 @@ static int save_external_coredump(const char *info[_INFO_LEN], goto fail; } - /* Ignore errors on these */ - fchmod(fd, 0640); - fix_acl(fd, uid); - fix_xattr(fd, info); - - if (fsync(fd) < 0) { - log_error("Failed to sync coredump %s: %m", tmp); - r = -errno; - goto fail; + if (lseek(fd, 0, SEEK_SET) == (off_t) -1) { + log_error("Failed to seek on %s: %m", tmp); + goto uncompressed; } if (fstat(fd, &st) < 0) { log_error("Failed to fstat coredump %s: %m", tmp); - r = -errno; goto fail; } - if (rename(tmp, fn) < 0) { - log_error("Failed to rename coredump %s -> %s: %m", tmp, fn); - r = -errno; - goto fail; +#ifdef HAVE_XZ + /* If we will remove the coredump anyway, do not compress. */ + if (maybe_remove_external_coredump(NULL, st.st_size) == 0) { + + _cleanup_free_ char *fn2 = NULL; + char *tmp2; + _cleanup_close_ int fd2 = -1; + + tmp2 = strappenda(tmp, ".xz"); + fd2 = open(tmp2, O_CREAT|O_EXCL|O_RDWR|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW, 0640); + if (fd2 < 0) { + log_error("Failed to create file %s: %m", tmp2); + goto uncompressed; + } + + r = compress_stream(fd, fd2, -1); + if (r < 0) { + log_error("Failed to compress %s: %s", tmp2, strerror(-r)); + unlink_noerrno(tmp2); + goto fail2; + } + + fn2 = strappend(fn, ".xz"); + if (!fn2) { + log_oom(); + goto fail2; + } + + r = fix_permissions(fd2, tmp2, fn2, info, uid); + if (r < 0) + goto fail2; + + *ret_filename = fn2; /* compressed */ + *ret_fd = fd; /* uncompressed */ + *ret_size = st.st_size; /* uncompressed */ + + fn2 = NULL; + fd = -1; + + return 0; + + fail2: + unlink_noerrno(tmp2); } +#endif +uncompressed: *ret_filename = fn; *ret_fd = fd; *ret_size = st.st_size; @@ -317,7 +393,7 @@ static int allocate_journal_field(int fd, size_t size, char **ret, size_t *ret_s field = malloc(9 + size); if (!field) { - log_warning("Failed to allocate memory fore coredump, coredump will not be stored."); + log_warning("Failed to allocate memory for coredump, coredump will not be stored."); return -ENOMEM; } @@ -341,23 +417,6 @@ static int allocate_journal_field(int fd, size_t size, char **ret, size_t *ret_s return 0; } -static int maybe_remove_external_coredump(const char *filename, off_t size) { - - if (!filename) - return 0; - - if (IN_SET(arg_storage, COREDUMP_STORAGE_EXTERNAL, COREDUMP_STORAGE_BOTH) && - size <= arg_external_size_max) - return 0; - - if (unlink(filename) < 0) { - log_error("Failed to unlink %s: %m", filename); - return -errno; - } - - return 0; -} - int main(int argc, char* argv[]) { _cleanup_free_ char *core_pid = NULL, *core_uid = NULL, *core_gid = NULL, *core_signal = NULL, -- 2.0.0.rc4 _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel