[PATCH v2] ksmbd: set fixed sector size to FS_SECTOR_SIZE_INFORMATION

[Namjae Jeon <linkinjeon@kernel.org>]

Currently ksmbd is using ->f_bsize from vfs_statfs() as sector size.
If fat/exfat is a local share, ->f_bsize is a cluster size that is too
large to be used as a sector size. Sector sizes larger than 4K cause
problem occurs when mounting an iso file through windows client.

The error message can be obtained using Mount-DiskImage command,
 the error is:
"Mount-DiskImage : The sector size of the physical disk on which the
virtual disk resides is not supported."

This patch reports fixed 4KB sector size if ->s_blocksize is bigger
than 4KB.

Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
---
 v2:
  - set fixed 4KB sector size if ->s_blocksize is bigger than 4KB.

 fs/ksmbd/smb2pdu.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index 62cc0f95ab87..fe303c8ed87c 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -4995,15 +4995,17 @@ static int smb2_get_info_filesystem(struct ksmbd_work *work,
 	case FS_SECTOR_SIZE_INFORMATION:
 	{
 		struct smb3_fs_ss_info *info;
+		unsigned int sector_size =
+			min_t(unsigned int, path.mnt->mnt_sb->s_blocksize, 4096);
 
 		info = (struct smb3_fs_ss_info *)(rsp->Buffer);
 
-		info->LogicalBytesPerSector = cpu_to_le32(stfs.f_bsize);
+		info->LogicalBytesPerSector = cpu_to_le32(sector_size);
 		info->PhysicalBytesPerSectorForAtomicity =
-				cpu_to_le32(stfs.f_bsize);
-		info->PhysicalBytesPerSectorForPerf = cpu_to_le32(stfs.f_bsize);
+				cpu_to_le32(sector_size);
+		info->PhysicalBytesPerSectorForPerf = cpu_to_le32(sector_size);
 		info->FSEffPhysicalBytesPerSectorForAtomicity =
-				cpu_to_le32(stfs.f_bsize);
+				cpu_to_le32(sector_size);
 		info->Flags = cpu_to_le32(SSINFO_FLAGS_ALIGNED_DEVICE |
 				    SSINFO_FLAGS_PARTITION_ALIGNED_ON_DEVICE);
 		info->ByteOffsetForSectorAlignment = 0;
-- 
2.25.1