[PATCH v2] common/rc: add _require_blocks_in_file helper

[PATCH v2] common/rc: add _require_blocks_in_file helper

[Joanne Chang]

generic/735 attempts to create a file with nearly 2^32 blocks. However,
some filesystems have a maximum file block limit below this threshold.
For instance, F2FS is limited to approximately 2^30 blocks due to the
capacity of the inode. So add _require_blocks_in_file helper to skip the
test in such cases.

Signed-off-by: Joanne Chang <joannechien@google.com>
---
v1 -> v2:
- changed title from "generic/735: disable for f2fs"
- used a new helper function instead of _exclude_fs as Christoph Hellwig
  suggested

 common/rc         | 16 ++++++++++++++++
 tests/generic/735 |  1 +
 2 files changed, 17 insertions(+)

diff --git a/common/rc b/common/rc
index c3cdc220..e92f4854 100644
--- a/common/rc
+++ b/common/rc
@@ -6120,6 +6120,22 @@ _require_file_attr_special()
 	fi
 }
 
+# Require filesystem to accomodate enough blocks in a file
+_require_blocks_in_file()
+{
+	local blocks=$1
+
+	case $FSTYP in
+	f2fs)
+		if [ $blocks -gt 1057053439 ]; then
+			_notrun "$blocks blocks per file not supported on $FSTYP"
+		fi
+		;;
+	*)
+		;;
+	esac
+}
+
 ################################################################################
 # make sure this script returns success
 /bin/true
diff --git a/tests/generic/735 b/tests/generic/735
index 9bbdf3a1..2fbf125c 100755
--- a/tests/generic/735
+++ b/tests/generic/735
@@ -22,6 +22,7 @@ fi
 _require_odirect
 _require_xfs_io_command "falloc"
 _require_xfs_io_command "finsert"
+_require_blocks_in_file $(( (1 << 32) - 1 ))
 
 dev_size=$((80 * 1024 * 1024))
 _scratch_mkfs_sized $dev_size >>$seqres.full 2>&1
-- 
2.52.0.322.g1dd061c0dc-goog

Re: [PATCH v2] common/rc: add _require_blocks_in_file helper

[Chao Yu]

On 12/29/2025 10:31 AM, Joanne Chang wrote:
> generic/735 attempts to create a file with nearly 2^32 blocks. However,
> some filesystems have a maximum file block limit below this threshold.
> For instance, F2FS is limited to approximately 2^30 blocks due to the
> capacity of the inode. So add _require_blocks_in_file helper to skip the
> test in such cases.
> 
> Signed-off-by: Joanne Chang <joannechien@google.com>

Reviewed-by: Chao Yu <chao@kernel.org>

Thanks,

Re: [PATCH v2] common/rc: add _require_blocks_in_file helper

[Christoph Hellwig]

On Mon, Dec 29, 2025 at 02:31:45AM +0000, Joanne Chang wrote:
> generic/735 attempts to create a file with nearly 2^32 blocks. However,
> some filesystems have a maximum file block limit below this threshold.
> For instance, F2FS is limited to approximately 2^30 blocks due to the
> capacity of the inode. So add _require_blocks_in_file helper to skip the
> test in such cases.

I still don't understand why we can't do this programmatically.  I guess
it would be simply too slow?  In that case that should probably be
documented here in the commit log.  Otherwise this looks good to me.

Re: [PATCH v2] common/rc: add _require_blocks_in_file helper

[Joanne Chang]

On Wed, Jan 7, 2026 at 2:08 PM Christoph Hellwig <hch@infradead.org> wrote:
> I still don't understand why we can't do this programmatically.  I guess
> it would be simply too slow?  In that case that should probably be
> documented here in the commit log.  Otherwise this looks good to me.

I used a constant to avoid masking bugs that cause the maximum file size
to shrink on filesystems that should support this test. I can add the
reason to the commit message if that would make it clearer.

Best regards,
Joanne

Re: [PATCH v2] common/rc: add _require_blocks_in_file helper

[Christoph Hellwig]

On Wed, Jan 07, 2026 at 04:12:44PM +0800, Joanne Chang wrote:
> On Wed, Jan 7, 2026 at 2:08 PM Christoph Hellwig <hch@infradead.org> wrote:
> > I still don't understand why we can't do this programmatically.  I guess
> > it would be simply too slow?  In that case that should probably be
> > documented here in the commit log.  Otherwise this looks good to me.
> 
> I used a constant to avoid masking bugs that cause the maximum file size
> to shrink on filesystems that should support this test. I can add the
> reason to the commit message if that would make it clearer.

That would be great, thanks!