fsck: Automatically use kernel fsck when better version match

To avoid expensive version upgrades and downgrades - use the kernel
version of fsck when it's availale and a better match.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/c_src/cmd_fsck.c b/c_src/cmd_fsck.c
index 262ac1bcde02012c64a30fa2798b2ab130dceb9d..79f520076bb204703e4bfa1e7908bad98709fbe4 100644 (file)
--- a/c_src/cmd_fsck.c
+++ b/c_src/cmd_fsck.c
@@ -6,6 +6,7 @@
 #include "libbcachefs/error.h"
 #include "libbcachefs.h"
 #include "libbcachefs/super.h"
+#include "libbcachefs/super-io.h"
 #include "tools-util.h"
 
 static void fsck_usage(void)
@@ -68,10 +69,13 @@ static int splice_fd_to_stdinout(int fd)
 
                select(fd + 1, &fds, NULL, NULL, NULL);
 
-               int r = do_splice(fd, STDOUT_FILENO) ?:
-                       do_splice(STDIN_FILENO, fd);
+               int r = do_splice(fd, STDOUT_FILENO);
                if (r)
                        return r < 0 ? r : 0;
+
+               r = do_splice(STDIN_FILENO, fd);
+               if (r < 0)
+                       return r;
        }
 
        return 0;
@@ -98,16 +102,64 @@ static void append_opt(struct printbuf *out, const char *opt)
        prt_str(out, opt);
 }
 
+static bool should_use_kernel_fsck(darray_str devs)
+{
+       unsigned kernel_version = !access("/sys/module/bcachefs/parameters/version", R_OK)
+           ? read_file_u64(AT_FDCWD, "/sys/module/bcachefs/parameters/version")
+           : 0;
+
+       if (!kernel_version)
+               return false;
+
+       if (kernel_version == bcachefs_metadata_version_current)
+               return false;
+
+       struct bch_opts opts = bch2_opts_empty();
+       opt_set(opts, nostart, true);
+       opt_set(opts, noexcl, true);
+       opt_set(opts, nochanges, true);
+       opt_set(opts, read_only, true);
+
+       struct bch_fs *c = bch2_fs_open(devs.data, devs.nr, opts);
+       if (IS_ERR(c))
+               return false;
+
+       bool ret = ((bcachefs_metadata_version_current < kernel_version &&
+                    kernel_version <= c->sb.version) ||
+                   (c->sb.version <= kernel_version &&
+                    kernel_version < bcachefs_metadata_version_current));
+
+       if (ret) {
+               struct printbuf buf = PRINTBUF;
+
+               prt_str(&buf, "fsck binary is version ");
+               bch2_version_to_text(&buf, bcachefs_metadata_version_current);
+               prt_str(&buf, " but filesystem is ");
+               bch2_version_to_text(&buf, c->sb.version);
+               prt_str(&buf, " and kernel is ");
+               bch2_version_to_text(&buf, kernel_version);
+               prt_str(&buf, ", using kernel fsck\n");
+
+               printf("%s", buf.buf);
+               printbuf_exit(&buf);
+       }
+
+       bch2_fs_stop(c);
+
+       return ret;
+}
+
 int cmd_fsck(int argc, char *argv[])
 {
        static const struct option longopts[] = {
                { "ratelimit_errors",   no_argument,            NULL, 'r' },
                { "reconstruct_alloc",  no_argument,            NULL, 'R' },
                { "kernel",             no_argument,            NULL, 'k' },
+               { "no-kernel",          no_argument,            NULL, 'K' },
                { "help",               no_argument,            NULL, 'h' },
                { NULL }
        };
-       bool kernel = false;
+       int kernel = -1; /* unset */
        int opt, ret = 0;
        struct printbuf opts_str = PRINTBUF;
 
@@ -144,6 +196,9 @@ int cmd_fsck(int argc, char *argv[])
                case 'k':
                        kernel = true;
                        break;
+               case 'K':
+                       kernel = false;
+                       break;
                case 'v':
                        append_opt(&opts_str, "verbose");
                        break;
@@ -160,6 +215,9 @@ int cmd_fsck(int argc, char *argv[])
 
        darray_str devs = get_or_split_cmdline_devs(argc, argv);
 
+       if (kernel < 0)
+               kernel = should_use_kernel_fsck(devs);
+
        if (!kernel) {
                struct bch_opts opts = bch2_opts_empty();
                ret = bch2_parse_mount_opts(NULL, &opts, opts_str.buf);