fuse2fs: fix incorrect EOFS input handling in FITRIM

FITRIM isn't well documented, which means that I missed that
len == -1ULL always means "trim to end of filesystem".  generic/260 has
been failing with:

--- a/tests/generic/260.out      2025-04-30 16:20:44.532797310 -0700
+++ b/tests/generic/260.out.bad        2025-07-03 11:44:26.946394170 -0700
@@ -11,4 +11,5 @@
 [+] Default length with start set (should succeed)
 [+] Length beyond the end of fs (should succeed)
 [+] Length beyond the end of fs with start set (should succeed)
+After the full fs discard 0 bytes were discarded however the file system is 10401542144 bytes long.
 Test done

because the addition used to compute end suffered an integer overflow,
resulting in end < start, which meant nothing happened.  Fix this by
explicitly checking for -1ULL.

Cc: linux-ext4@vger.kernel.org # v1.43
Fixes: 81cbf1ef4f5dab ("misc: add fuse2fs, a FUSE server for e2fsprogs")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 5b866aed98237ff147d12bca4353eb6662bb3afe..34eaad1573132fa834d18c4070d9c903a04eebd1 100644 (file)
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -3775,7 +3775,10 @@ static int ioctl_fitrim(struct fuse2fs *ff, struct fuse2fs_file_handle *fh,
                return -EROFS;
 
        start = FUSE2FS_B_TO_FSBT(ff, fr->start);
-       end = FUSE2FS_B_TO_FSBT(ff, fr->start + fr->len - 1);
+       if (fr->len == -1ULL)
+               end = -1ULL;
+       else
+               end = FUSE2FS_B_TO_FSBT(ff, fr->start + fr->len - 1);
        minlen = FUSE2FS_B_TO_FSBT(ff, fr->minlen);
 
        if (EXT2FS_NUM_B2C(fs, minlen) > EXT2_CLUSTERS_PER_GROUP(fs->super) ||