hfsplus: fix error code when writing beyond volume capacity

The xfstests' test-case generic/564 fails for
the case of HFS+ file system. Test-case expects that
file system driver reports -EFBIG error code in the case
if there is the effort to write beyond 8TiB. However, HFS+
file system driver returns -ENOSPC instead.

The root cause is that hfsplus_fill_super() sets s_maxbytes
as MAX_LFS_FILESIZE. VFS therefore considers the write
position valid and calls into the filesystem. Because HFS+
does not support holes, cont_write_begin() zero-fills
the entire intermediate range from the current end-of-file
to the target offset. On a small test volume this exhausts
free space long before any block-number overflow is detected,
producing -ENOSPC instead of -EFBIG.

This patch fixes the issue by adding a bounds check at
the top of hfsplus_write_begin(). If the requested write
position is at or beyond the actual capacity of the volume
in bytes, return -EFBIG immediately before cont_write_begin()
is entered and before any zero-fill I/O is attempted.

sudo ./check generic/564
FSTYP         -- hfsplus
PLATFORM      -- Linux/x86_64 hfsplus-testing-0001 7.2.0-rc1-dirty #50 SMP PREEMPT_DYNAMIC Fri Jul  3 16:22:27 PDT 2026
MKFS_OPTIONS  -- /dev/loop51
MOUNT_OPTIONS -- /dev/loop51 /mnt/scratch

generic/564  13s ...  43s
Ran: generic/564
Passed all 1 tests

cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
cc: Yangtao Li <frank.li@vivo.com>
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
Link: https://lore.kernel.org/r/20260706221738.140271-2-slava@dubeyko.com
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/fs/hfsplus/inode.c b/fs/hfsplus/inode.c
index 1c57c873f05d..2ce6de574fa6 100644
--- a/fs/hfsplus/inode.c
+++ b/fs/hfsplus/inode.c
@@ -43,11 +43,19 @@ int hfsplus_write_begin(const struct kiocb *iocb,
 			unsigned len, struct folio **foliop,
 			void **fsdata)
 {
+	struct inode *inode = mapping->host;
+	struct hfsplus_sb_info *sbi = HFSPLUS_SB(inode->i_sb);
+	loff_t total_capacity;
 	int ret;
 
+	total_capacity = (loff_t)sbi->total_blocks << sbi->alloc_blksz_shift;
+
+	if (pos >= total_capacity)
+		return -EFBIG;
+
 	ret = cont_write_begin(iocb, mapping, pos, len, foliop, fsdata,
 				hfsplus_get_block,
-				&HFSPLUS_I(mapping->host)->phys_size);
+				&HFSPLUS_I(inode)->phys_size);
 	if (unlikely(ret))
 		hfsplus_write_failed(mapping, pos + len);