[PATCH v4 1/7] smb/client: refresh allocation size after duplicate extents

[Huiwen He <huiwen.he@linux.dev>]

From: Huiwen He <hehuiwen@kylinos.cn>

FSCTL_DUPLICATE_EXTENTS_TO_FILE changes the target file extents on the
server, but the client does not refresh the target AllocationSize/i_blocks.
Callers can observe or use the wrong st_blocks value immediately after the
clone, before a later attribute revalidation corrects it.

For example, create a reflinked file with a leading hole:

        xfs_io -f -c "pwrite -S 0x61 0 64k" src
        touch dst
        chmod 600 dst
        xfs_io -c "reflink src 0 1m 64k" dst
        mkswap dst
        swapon dst

The file still has a hole after mkswap:

        /mnt/scratch/dst:
          [0..7]:       allocated
          [8..2047]:    hole
          [2048..2175]: allocated

The server also reports only the allocated ranges:

        server dst size=1114112 blocks=144

but the client reported EOF-derived blocks:

        client dst size=1114112 blocks=2176

and swapon succeeded:

        swapon_result=success
        /mnt/scratch/dst 1.1M 0B -1

So EOF-derived i_blocks can let a sparse reflinked file pass the CIFS
swapfile hole check.

Fix this by querying FILE_ALL_INFORMATION on the target handle after a
successful duplicate extents request and updating i_blocks from the
returned AllocationSize. If the query fails, invalidate the cached
inode attributes so a later getattr can refresh them.

Signed-off-by: Huiwen He <hehuiwen@kylinos.cn>
Reviewed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
---
 fs/smb/client/smb2ops.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index 965a4d21dd43..f13e5d902244 100644
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -2193,10 +2193,13 @@ smb2_duplicate_extents(const unsigned int xid,
 			u64 len, u64 dest_off)
 {
 	int rc;
+	int qrc;
 	unsigned int ret_data_len;
 	struct inode *inode;
+	struct smb2_file_all_info file_inf;
 	struct duplicate_extents_to_file dup_ext_buf;
 	struct cifs_tcon *tcon = tlink_tcon(trgtfile->tlink);
+	u64 asize;
 
 	/* server fileays advertise duplicate extent support with this flag */
 	if ((le32_to_cpu(tcon->fsAttrInfo.Attributes) &
@@ -2232,6 +2235,19 @@ smb2_duplicate_extents(const unsigned int xid,
 	if (ret_data_len > 0)
 		cifs_dbg(FYI, "Non-zero response length in duplicate extents\n");
 
+	if (rc == 0) {
+		qrc = SMB2_query_info(xid, tcon, trgtfile->fid.persistent_fid,
+				      trgtfile->fid.volatile_fid, &file_inf);
+		spin_lock(&inode->i_lock);
+		if (qrc == 0) {
+			asize = le64_to_cpu(file_inf.AllocationSize);
+			inode->i_blocks = CIFS_INO_BLOCKS(asize);
+		} else {
+			CIFS_I(inode)->time = 0; /* force reval */
+		}
+		spin_unlock(&inode->i_lock);
+	}
+
 duplicate_extents_out:
 	if (rc)
 		trace_smb3_clone_err(xid, srcfile->fid.volatile_fid,
-- 
2.43.0