From: Henrique Carvalho <henrique.carvalho@suse.com>
To: sfrench@samba.org
Cc: pc@manguebit.org, ronniesahlberg@gmail.com,
sprasad@microsoft.com, tom@talpey.com, bharathsm@microsoft.com,
ematsumiya@suse.de, linux-cifs@vger.kernel.org,
Henrique Carvalho <henrique.carvalho@suse.com>
Subject: [PATCH v4] smb: client: batch SRV_COPYCHUNK entries to cut round trips
Date: Fri, 3 Oct 2025 23:11:43 -0300 [thread overview]
Message-ID: <20251004021143.230223-1-henrique.carvalho@suse.com> (raw)
smb2_copychunk_range() used to send a single SRV_COPYCHUNK per
SRV_COPYCHUNK_COPY IOCTL.
Implement variable Chunks[] array in struct copychunk_ioctl and fill it
with struct copychunk (MS-SMB2 2.2.31.1.1), bounded by server-advertised
limits.
This reduces the number of IOCTL requests for large copies.
While we are at it, rename a couple variables to follow the terminology
used in the specification.
Signed-off-by: Henrique Carvalho <henrique.carvalho@suse.com>
---
V3 -> V4:
- fix min_t truncation to u32 issue in calc_chunk_count
V2 -> V3:
- guard against potential "Invented loads" in calc_chunk_count
(see https://lwn.net/Articles/793253/#Invented%20Loads -- please
let me know if I'm misunderstanding the concept)
- improved comments and variable naming in calc_chunk_count
- minor documentation improvement
- stop log flooding (reported by Paulo Alcantara): return early on rc &&
rc != -EINVAL right after SMB2_ioctl; only validate cc_rsp size when
rc == 0 or rc == -EINVAL
- restructure code; drop *_iter trace; fix a comment typo (per Enzo Matsumiya)
- downgrade debug level from VFS to FYI on -EINVAL (per Steve French)
V1 -> V2:
- initialize ret_data_len to 0 (per Dan Carpenter)
fs/smb/client/smb2ops.c | 306 +++++++++++++++++++++++++---------------
fs/smb/client/smb2pdu.h | 16 ++-
fs/smb/client/trace.h | 2 +-
3 files changed, 207 insertions(+), 117 deletions(-)
fs/smb/client/smb2ops.c | 306 +++++++++++++++++++++++++---------------
fs/smb/client/smb2pdu.h | 16 ++-
fs/smb/client/trace.h | 2 +-
3 files changed, 207 insertions(+), 117 deletions(-)
diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index 058050f744c0..80114292e2c9 100644
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -1803,140 +1803,226 @@ smb2_ioctl_query_info(const unsigned int xid,
return rc;
}
+/**
+ * calc_chunk_count - calculates the number chunks to be filled in the Chunks[]
+ * array of struct copychunk_ioctl
+ *
+ * @tcon: destination file tcon
+ * @bytes_left: how many bytes are left to copy
+ *
+ * Return: maximum number of chunks with which Chunks[] can be filled.
+ */
+static inline u32
+calc_chunk_count(struct cifs_tcon *tcon, u64 bytes_left)
+{
+ u32 max_chunks = READ_ONCE(tcon->max_chunks);
+ u32 max_bytes_copy = READ_ONCE(tcon->max_bytes_copy);
+ u32 max_bytes_chunk = READ_ONCE(tcon->max_bytes_chunk);
+ u64 need;
+ u32 allowed;
+
+ if (!max_bytes_chunk || !max_bytes_copy || !max_chunks)
+ return 0;
+
+ /* chunks needed for the remaining bytes */
+ need = DIV_ROUND_UP_ULL(bytes_left, max_bytes_chunk);
+ /* chunks allowed per cc request */
+ allowed = DIV_ROUND_UP(max_bytes_copy, max_bytes_chunk);
+
+ return (u32)umin(need, umin(max_chunks, allowed));
+}
+
+/**
+ * smb2_copychunk_range - server-side copy of data range
+ *
+ * @xid: transaction id
+ * @src_file: source file
+ * @dst_file: destination file
+ * @src_off: source file byte offset
+ * @len: number of bytes to copy
+ * @dst_off: destination file byte offset
+ *
+ * Obtains a resume key for @src_file and issues FSCTL_SRV_COPYCHUNK_WRITE
+ * IOCTLs, splitting the request into chunks limited by tcon->max_*.
+ *
+ * Return: @len on success; negative errno on failure.
+ */
static ssize_t
smb2_copychunk_range(const unsigned int xid,
- struct cifsFileInfo *srcfile,
- struct cifsFileInfo *trgtfile, u64 src_off,
- u64 len, u64 dest_off)
+ struct cifsFileInfo *src_file,
+ struct cifsFileInfo *dst_file,
+ u64 src_off,
+ u64 len,
+ u64 dst_off)
{
- int rc;
- unsigned int ret_data_len;
- struct copychunk_ioctl *pcchunk;
- struct copychunk_ioctl_rsp *retbuf = NULL;
+ int rc = 0;
+ unsigned int ret_data_len = 0;
+ struct copychunk_ioctl *cc_req = NULL;
+ struct copychunk_ioctl_rsp *cc_rsp = NULL;
struct cifs_tcon *tcon;
- int chunks_copied = 0;
- bool chunk_sizes_updated = false;
- ssize_t bytes_written, total_bytes_written = 0;
+ struct copychunk *chunk;
+ u32 chunks, chunk_count, chunk_bytes;
+ u32 copy_bytes, copy_bytes_left;
+ u32 chunks_written, bytes_written;
+ u64 total_bytes_left = len;
+ u64 src_off_prev, dst_off_prev;
+ u32 retries = 0;
+
+ tcon = tlink_tcon(dst_file->tlink);
+
+ trace_smb3_copychunk_enter(xid, src_file->fid.volatile_fid,
+ dst_file->fid.volatile_fid, tcon->tid,
+ tcon->ses->Suid, src_off, dst_off, len);
+
+retry:
+ chunk_count = calc_chunk_count(tcon, total_bytes_left);
+ if (!chunk_count) {
+ rc = -EOPNOTSUPP;
+ goto out;
+ }
- pcchunk = kmalloc(sizeof(struct copychunk_ioctl), GFP_KERNEL);
- if (pcchunk == NULL)
- return -ENOMEM;
+ cc_req = kzalloc(struct_size(cc_req, Chunks, chunk_count), GFP_KERNEL);
+ if (!cc_req) {
+ rc = -ENOMEM;
+ goto out;
+ }
- cifs_dbg(FYI, "%s: about to call request res key\n", __func__);
/* Request a key from the server to identify the source of the copy */
- rc = SMB2_request_res_key(xid, tlink_tcon(srcfile->tlink),
- srcfile->fid.persistent_fid,
- srcfile->fid.volatile_fid, pcchunk);
+ rc = SMB2_request_res_key(xid,
+ tlink_tcon(src_file->tlink),
+ src_file->fid.persistent_fid,
+ src_file->fid.volatile_fid,
+ cc_req);
- /* Note: request_res_key sets res_key null only if rc !=0 */
+ /* Note: request_res_key sets res_key null only if rc != 0 */
if (rc)
- goto cchunk_out;
+ goto out;
- /* For now array only one chunk long, will make more flexible later */
- pcchunk->ChunkCount = cpu_to_le32(1);
- pcchunk->Reserved = 0;
- pcchunk->Reserved2 = 0;
+ while (total_bytes_left > 0) {
- tcon = tlink_tcon(trgtfile->tlink);
+ /* Store previous offsets to allow rewind */
+ src_off_prev = src_off;
+ dst_off_prev = dst_off;
- trace_smb3_copychunk_enter(xid, srcfile->fid.volatile_fid,
- trgtfile->fid.volatile_fid, tcon->tid,
- tcon->ses->Suid, src_off, dest_off, len);
+ chunks = 0;
+ copy_bytes = 0;
+ copy_bytes_left = umin(total_bytes_left, tcon->max_bytes_copy);
+ while (copy_bytes_left > 0 && chunks < chunk_count) {
+ chunk = &cc_req->Chunks[chunks++];
- while (len > 0) {
- pcchunk->SourceOffset = cpu_to_le64(src_off);
- pcchunk->TargetOffset = cpu_to_le64(dest_off);
- pcchunk->Length =
- cpu_to_le32(min_t(u64, len, tcon->max_bytes_chunk));
+ chunk->SourceOffset = cpu_to_le64(src_off);
+ chunk->TargetOffset = cpu_to_le64(dst_off);
+
+ chunk_bytes = umin(copy_bytes_left, tcon->max_bytes_chunk);
+
+ chunk->Length = cpu_to_le32(chunk_bytes);
+ /* Buffer is zeroed, no need to set chunk->Reserved = 0 */
+
+ src_off += chunk_bytes;
+ dst_off += chunk_bytes;
+
+ copy_bytes_left -= chunk_bytes;
+ copy_bytes += chunk_bytes;
+ }
+
+ cc_req->ChunkCount = cpu_to_le32(chunks);
+ /* Buffer is zeroed, no need to set cc_req->Reserved = 0 */
/* Request server copy to target from src identified by key */
- kfree(retbuf);
- retbuf = NULL;
- rc = SMB2_ioctl(xid, tcon, trgtfile->fid.persistent_fid,
- trgtfile->fid.volatile_fid, FSCTL_SRV_COPYCHUNK_WRITE,
- (char *)pcchunk, sizeof(struct copychunk_ioctl),
- CIFSMaxBufSize, (char **)&retbuf, &ret_data_len);
+ kfree(cc_rsp);
+ cc_rsp = NULL;
+ rc = SMB2_ioctl(xid, tcon, dst_file->fid.persistent_fid,
+ dst_file->fid.volatile_fid, FSCTL_SRV_COPYCHUNK_WRITE,
+ (char *)cc_req, struct_size(cc_req, Chunks, chunks),
+ CIFSMaxBufSize, (char **)&cc_rsp, &ret_data_len);
+
+ if (rc && rc != -EINVAL)
+ goto out;
+
+ if (unlikely(ret_data_len != sizeof(*cc_rsp))) {
+ cifs_tcon_dbg(VFS, "Copychunk invalid response: size %u/%zu\n",
+ ret_data_len, sizeof(*cc_rsp));
+ rc = -EIO;
+ goto out;
+ }
+
+ bytes_written = le32_to_cpu(cc_rsp->TotalBytesWritten);
+ chunks_written = le32_to_cpu(cc_rsp->ChunksWritten);
+ chunk_bytes = le32_to_cpu(cc_rsp->ChunkBytesWritten);
+
if (rc == 0) {
- if (ret_data_len !=
- sizeof(struct copychunk_ioctl_rsp)) {
- cifs_tcon_dbg(VFS, "Invalid cchunk response size\n");
- rc = -EIO;
- goto cchunk_out;
- }
- if (retbuf->TotalBytesWritten == 0) {
- cifs_dbg(FYI, "no bytes copied\n");
- rc = -EIO;
- goto cchunk_out;
- }
- /*
- * Check if server claimed to write more than we asked
- */
- if (le32_to_cpu(retbuf->TotalBytesWritten) >
- le32_to_cpu(pcchunk->Length)) {
- cifs_tcon_dbg(VFS, "Invalid copy chunk response\n");
+ /* Check if server claimed to write more than we asked */
+ if (unlikely(!bytes_written || bytes_written > copy_bytes ||
+ !chunks_written || chunks_written > chunks)) {
+ cifs_tcon_dbg(VFS, "Copychunk invalid response: bytes written %u/%u, chunks written %u/%u\n",
+ bytes_written, copy_bytes, chunks_written, chunks);
rc = -EIO;
- goto cchunk_out;
+ goto out;
}
- if (le32_to_cpu(retbuf->ChunksWritten) != 1) {
- cifs_tcon_dbg(VFS, "Invalid num chunks written\n");
- rc = -EIO;
- goto cchunk_out;
+
+ /* Partial write: rewind */
+ if (bytes_written < copy_bytes) {
+ u32 delta = copy_bytes - bytes_written;
+
+ src_off -= delta;
+ dst_off -= delta;
}
- chunks_copied++;
-
- bytes_written = le32_to_cpu(retbuf->TotalBytesWritten);
- src_off += bytes_written;
- dest_off += bytes_written;
- len -= bytes_written;
- total_bytes_written += bytes_written;
-
- cifs_dbg(FYI, "Chunks %d PartialChunk %d Total %zu\n",
- le32_to_cpu(retbuf->ChunksWritten),
- le32_to_cpu(retbuf->ChunkBytesWritten),
- bytes_written);
- trace_smb3_copychunk_done(xid, srcfile->fid.volatile_fid,
- trgtfile->fid.volatile_fid, tcon->tid,
- tcon->ses->Suid, src_off, dest_off, len);
- } else if (rc == -EINVAL) {
- if (ret_data_len != sizeof(struct copychunk_ioctl_rsp))
- goto cchunk_out;
-
- cifs_dbg(FYI, "MaxChunks %d BytesChunk %d MaxCopy %d\n",
- le32_to_cpu(retbuf->ChunksWritten),
- le32_to_cpu(retbuf->ChunkBytesWritten),
- le32_to_cpu(retbuf->TotalBytesWritten));
- /*
- * Check if this is the first request using these sizes,
- * (ie check if copy succeed once with original sizes
- * and check if the server gave us different sizes after
- * we already updated max sizes on previous request).
- * if not then why is the server returning an error now
- */
- if ((chunks_copied != 0) || chunk_sizes_updated)
- goto cchunk_out;
-
- /* Check that server is not asking us to grow size */
- if (le32_to_cpu(retbuf->ChunkBytesWritten) <
- tcon->max_bytes_chunk)
- tcon->max_bytes_chunk =
- le32_to_cpu(retbuf->ChunkBytesWritten);
- else
- goto cchunk_out; /* server gave us bogus size */
+ total_bytes_left -= bytes_written;
+ continue;
+ }
- /* No need to change MaxChunks since already set to 1 */
- chunk_sizes_updated = true;
- } else
- goto cchunk_out;
+ /*
+ * Check if server is not asking us to reduce size.
+ *
+ * Note: As per MS-SMB2 2.2.32.1, the values returned
+ * in cc_rsp are not strictly lower than what existed
+ * before.
+ */
+ if (bytes_written < tcon->max_bytes_copy) {
+ cifs_tcon_dbg(FYI, "Copychunk MaxBytesCopy updated: %u -> %u\n",
+ tcon->max_bytes_copy, bytes_written);
+ tcon->max_bytes_copy = bytes_written;
+ }
+
+ if (chunks_written < tcon->max_chunks) {
+ cifs_tcon_dbg(FYI, "Copychunk MaxChunks updated: %u -> %u\n",
+ tcon->max_chunks, chunks_written);
+ tcon->max_chunks = chunks_written;
+ }
+
+ if (chunk_bytes < tcon->max_bytes_chunk) {
+ cifs_tcon_dbg(FYI, "Copychunk MaxBytesChunk updated: %u -> %u\n",
+ tcon->max_bytes_chunk, chunk_bytes);
+ tcon->max_bytes_chunk = chunk_bytes;
+ }
+
+ /* reset to last offsets */
+ if (retries++ < 2) {
+ src_off = src_off_prev;
+ dst_off = dst_off_prev;
+ kfree(cc_req);
+ cc_req = NULL;
+ goto retry;
+ }
+
+ break;
}
-cchunk_out:
- kfree(pcchunk);
- kfree(retbuf);
- if (rc)
+out:
+ kfree(cc_req);
+ kfree(cc_rsp);
+ if (rc) {
+ trace_smb3_copychunk_err(xid, src_file->fid.volatile_fid,
+ dst_file->fid.volatile_fid, tcon->tid,
+ tcon->ses->Suid, src_off, dst_off, len, rc);
return rc;
- else
- return total_bytes_written;
+ } else {
+ trace_smb3_copychunk_done(xid, src_file->fid.volatile_fid,
+ dst_file->fid.volatile_fid, tcon->tid,
+ tcon->ses->Suid, src_off, dst_off, len);
+ return len;
+ }
}
static int
diff --git a/fs/smb/client/smb2pdu.h b/fs/smb/client/smb2pdu.h
index 3c09a58dfd07..101024f8f725 100644
--- a/fs/smb/client/smb2pdu.h
+++ b/fs/smb/client/smb2pdu.h
@@ -201,16 +201,20 @@ struct resume_key_req {
char Context[]; /* ignored, Windows sets to 4 bytes of zero */
} __packed;
+
+struct copychunk {
+ __le64 SourceOffset;
+ __le64 TargetOffset;
+ __le32 Length;
+ __le32 Reserved;
+} __packed;
+
/* this goes in the ioctl buffer when doing a copychunk request */
struct copychunk_ioctl {
char SourceKey[COPY_CHUNK_RES_KEY_SIZE];
- __le32 ChunkCount; /* we are only sending 1 */
+ __le32 ChunkCount;
__le32 Reserved;
- /* array will only be one chunk long for us */
- __le64 SourceOffset;
- __le64 TargetOffset;
- __le32 Length; /* how many bytes to copy */
- __u32 Reserved2;
+ struct copychunk Chunks[];
} __packed;
struct copychunk_ioctl_rsp {
diff --git a/fs/smb/client/trace.h b/fs/smb/client/trace.h
index fd650e2afc76..28e00c34df1c 100644
--- a/fs/smb/client/trace.h
+++ b/fs/smb/client/trace.h
@@ -266,7 +266,7 @@ DEFINE_EVENT(smb3_copy_range_err_class, smb3_##name, \
TP_ARGS(xid, src_fid, target_fid, tid, sesid, src_offset, target_offset, len, rc))
DEFINE_SMB3_COPY_RANGE_ERR_EVENT(clone_err);
-/* TODO: Add SMB3_COPY_RANGE_ERR_EVENT(copychunk_err) */
+DEFINE_SMB3_COPY_RANGE_ERR_EVENT(copychunk_err);
DECLARE_EVENT_CLASS(smb3_copy_range_done_class,
TP_PROTO(unsigned int xid,
--
2.50.1
next reply other threads:[~2025-10-04 2:15 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-04 2:11 Henrique Carvalho [this message]
2025-10-04 2:51 ` [PATCH v4] smb: client: batch SRV_COPYCHUNK entries to cut round trips Steve French
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