fuse2fs: track our own writable state

Track our own willingness to write to the filesystem in a separate
variable from that of libext2fs.  There's a small window between opening
the filesystem and mounting it where the library is rw but we might fail
a mount task and therefore don't want to write anything more.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>

diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 5e32427d5957b4bb08932e3b533f0538ec23e293..a890060f38c74c0a2bcaac1cfc315c09def49865 100644 (file)
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -219,6 +219,11 @@ struct fuse2fs_file_handle {
        int check_flags;
 };
 
+enum fuse2fs_opstate {
+       F2OP_READONLY,
+       F2OP_WRITABLE,
+};
+
 /* Main program context */
 #define FUSE2FS_MAGIC          (0xEF53DEADUL)
 struct fuse2fs {
@@ -242,6 +247,7 @@ struct fuse2fs {
        int acl;
        int dirsync;
 
+       enum fuse2fs_opstate opstate;
        int logfd;
        int blocklog;
        int oom_score_adj;
@@ -553,7 +559,7 @@ static bool fuse2fs_mmp_wanted(const struct fuse2fs *ff)
        ext2_filsys fs = ff->fs;
 
        if (!fs || !ext2fs_has_feature_mmp(fs->super) ||
-           !(fs->flags & EXT2_FLAG_RW) || (fs->flags & EXT2_FLAG_SKIP_MMP))
+           ff->opstate != F2OP_WRITABLE || (fs->flags & EXT2_FLAG_SKIP_MMP))
                return false;
        return true;
 }
@@ -767,8 +773,6 @@ static int update_atime(ext2_filsys fs, ext2_ino_t ino)
        struct timespec atime, mtime, now;
        double datime, dmtime, dnow;
 
-       if (!(fs->flags & EXT2_FLAG_RW))
-               return 0;
        err = fuse2fs_read_inode(fs, ino, &inode);
        if (err)
                return translate_error(fs, ino, err);
@@ -884,9 +888,8 @@ static int fs_can_allocate(struct fuse2fs *ff, blk64_t num)
 
 static int fuse2fs_is_writeable(struct fuse2fs *ff)
 {
-       ext2_filsys fs = ff->fs;
-
-       return (fs->flags & EXT2_FLAG_RW) && (fs->super->s_error_count == 0);
+       return ff->opstate == F2OP_WRITABLE &&
+               (ff->fs->super->s_error_count == 0);
 }
 
 static inline int is_superuser(struct fuse2fs *ff, struct fuse_context *ctxt)
@@ -1135,6 +1138,7 @@ static errcode_t fuse2fs_open(struct fuse2fs *ff)
        }
 
        snprintf(options, sizeof(options) - 1, "offset=%lu", ff->offset);
+       ff->opstate = F2OP_READONLY;
 
        if (ff->directio)
                flags |= EXT2_FLAG_DIRECT_IO;
@@ -1337,6 +1341,7 @@ static int fuse2fs_mount(struct fuse2fs *ff)
  _("Warning: fuse2fs does not support using the journal.\n"
    "There may be file system corruption or data loss if\n"
    "the file system is not gracefully unmounted.\n"));
+               ff->opstate = F2OP_WRITABLE;
        }
 
        if (!(fs->super->s_state & EXT2_VALID_FS))
@@ -1359,7 +1364,7 @@ static int fuse2fs_mount(struct fuse2fs *ff)
                ff->errors_behavior = fs->super->s_errors;
 
        /* Clear the valid flag so that an unclean shutdown forces a fsck */
-       if (fs->flags & EXT2_FLAG_RW) {
+       if (ff->opstate == F2OP_WRITABLE) {
                fs->super->s_mnt_count++;
                ext2fs_set_tstamp(fs->super, s_mtime, time(NULL));
                fs->super->s_state &= ~EXT2_VALID_FS;
@@ -1383,7 +1388,7 @@ static void op_destroy(void *p EXT2FS_ATTR((unused)))
        fs = fuse2fs_start(ff);
 
        dbg_printf(ff, "%s: dev=%s\n", __func__, fs->device_name);
-       if (fs->flags & EXT2_FLAG_RW) {
+       if (ff->opstate == F2OP_WRITABLE) {
                fs->super->s_state |= EXT2_VALID_FS;
                if (fs->super->s_error_count)
                        fs->super->s_state |= EXT2_ERROR_FS;
@@ -1574,7 +1579,7 @@ static void *op_init(struct fuse_conn_info *conn
        cfg->nullpath_ok = 1;
 #endif
 
-       if (ff->fs->flags & EXT2_FLAG_RW)
+       if (ff->opstate == F2OP_WRITABLE)
                fuse2fs_read_bitmaps(ff);
 
        /*
@@ -3731,7 +3736,7 @@ static int op_statfs(const char *path EXT2FS_ATTR((unused)),
        fsid ^= *f;
        buf->f_fsid = fsid;
        buf->f_flag = 0;
-       if (!(fs->flags & EXT2_FLAG_RW))
+       if (ff->opstate != F2OP_WRITABLE)
                buf->f_flag |= ST_RDONLY;
        buf->f_namemax = EXT2_NAME_LEN;
        fuse2fs_finish(ff, 0);
@@ -5575,6 +5580,7 @@ int main(int argc, char *argv[])
                .logfd = -1,
                .bfl = (pthread_mutex_t)PTHREAD_MUTEX_INITIALIZER,
                .oom_score_adj = -500,
+               .opstate = F2OP_WRITABLE,
        };
        errcode_t err;
        FILE *orig_stderr = stderr;
@@ -5879,9 +5885,11 @@ static int __translate_error(ext2_filsys fs, ext2_ino_t ino, errcode_t err,
  _("Continuing after errors; is this a good idea?"));
                break;
        case EXT2_ERRORS_RO:
-               if (fs->flags & EXT2_FLAG_RW)
+               if (ff->opstate == F2OP_WRITABLE) {
                        err_printf(ff, "%s\n",
  _("Remounting read-only due to errors."));
+                       ff->opstate = F2OP_READONLY;
+               }
                fuse2fs_mmp_cancel(ff);
                fs->flags &= ~EXT2_FLAG_RW;
                break;