mirrors/linux
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2025-12-27 11:06:41 -05:00
Code Issues Packages Projects Releases Wiki Activity

cifs: client: enforce consistent handling of multichannel and max_channels

Browse Source 
Previously, the behavior of the multichannel and max_channels mount
options was inconsistent and order-dependent. For example, specifying
"multichannel,max_channels=1" would result in 2 channels, while
"max_channels=1,multichannel" would result in 1 channel. Additionally,
conflicting combinations such as "nomultichannel,max_channels=3" or
"multichannel,max_channels=1" did not produce errors and could lead to
unexpected channel counts.

This commit introduces two new fields in smb3_fs_context to explicitly
track whether multichannel and max_channels were specified during
mount. The option parsing and validation logic is updated to ensure:
- The outcome is no longer dependent on the order of options.
- Conflicting combinations (e.g., "nomultichannel,max_channels=3" or
  "multichannel,max_channels=1") are detected and result in an error.
- The number of channels created is consistent with the specified
  options.

This improves the reliability and predictability of mount option
handling for SMB3 multichannel support.

Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Rajasi Mandal <rajasimandal@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Rajasi Mandal
2025-11-18 02:26:55 +00:00
committed by Steve French
parent 869737543b
commit 1ef15fbe67
3 changed files with 50 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
fs/smb/client/cifsfs.c
View File

@@ -1016,7 +1016,6 @@ cifs_smb3_do_mount(struct file_system_type *fs_type,
} else {
cifs_info("Attempting to mount %s\n", old_ctx->source);
}
cifs_sb = kzalloc(sizeof(*cifs_sb), GFP_KERNEL);
if (!cifs_sb)
return ERR_PTR(-ENOMEM);

65
fs/smb/client/fs_context.c
View File

@@ -711,6 +711,47 @@ smb3_parse_devname(const char *devname, struct smb3_fs_context *ctx)
return 0;
}
static int smb3_handle_conflicting_options(struct fs_context *fc)
{
struct smb3_fs_context *ctx = smb3_fc2context(fc);
if (ctx->multichannel_specified) {
if (ctx->multichannel) {
if (!ctx->max_channels_specified) {
ctx->max_channels = 2;
} else if (ctx->max_channels == 1) {
cifs_errorf(fc,
"max_channels must be greater than 1 when multichannel is enabled\n");
return -EINVAL;
}
} else {
if (!ctx->max_channels_specified) {
ctx->max_channels = 1;
} else if (ctx->max_channels > 1) {
cifs_errorf(fc,
"max_channels must be equal to 1 when multichannel is disabled\n");
return -EINVAL;
}
}
} else {
if (ctx->max_channels_specified) {
if (ctx->max_channels > 1)
ctx->multichannel = true;
else
ctx->multichannel = false;
} else {
ctx->multichannel = false;
ctx->max_channels = 1;
}
}
//resetting default values as remount doesn't initialize fs_context again
ctx->multichannel_specified = false;
ctx->max_channels_specified = false;
return 0;
}
static void smb3_fs_context_free(struct fs_context *fc);
static int smb3_fs_context_parse_param(struct fs_context *fc,
struct fs_parameter *param);
@@ -784,6 +825,7 @@ static int smb3_fs_context_parse_monolithic(struct fs_context *fc,
if (ret < 0)
break;
}
ret = smb3_handle_conflicting_options(fc);
return ret;
}
@@ -1250,15 +1292,11 @@ static int smb3_fs_context_parse_param(struct fs_context *fc,
ctx->nodelete = 1;
break;
case Opt_multichannel:
if (result.negated) {
ctx->multichannel_specified = true;
if (result.negated)
ctx->multichannel = false;
ctx->max_channels = 1;
} else {
else
ctx->multichannel = true;
/* if number of channels not specified, default to 2 */
if (ctx->max_channels < 2)
ctx->max_channels = 2;
}
break;
case Opt_uid:
ctx->linux_uid = result.uid;
@@ -1394,15 +1432,13 @@ static int smb3_fs_context_parse_param(struct fs_context *fc,
ctx->max_credits = result.uint_32;
break;
case Opt_max_channels:
ctx->max_channels_specified = true;
if (result.uint_32 < 1 || result.uint_32 > CIFS_MAX_CHANNELS) {
cifs_errorf(fc, "%s: Invalid max_channels value, needs to be 1-%d\n",
__func__, CIFS_MAX_CHANNELS);
goto cifs_parse_mount_err;
}
ctx->max_channels = result.uint_32;
/* If more than one channel requested ... they want multichan */
if (result.uint_32 > 1)
ctx->multichannel = true;
break;
case Opt_max_cached_dirs:
if (result.uint_32 < 1) {
@@ -1820,13 +1856,6 @@ static int smb3_fs_context_parse_param(struct fs_context *fc,
goto cifs_parse_mount_err;
}
/*
* Multichannel is not meaningful if max_channels is 1.
* Force multichannel to false to ensure consistent configuration.
*/
if (ctx->multichannel && ctx->max_channels == 1)
ctx->multichannel = false;
return 0;
cifs_parse_mount_err:
@@ -1913,6 +1942,8 @@ int smb3_init_fs_context(struct fs_context *fc)
/* default to no multichannel (single server connection) */
ctx->multichannel = false;
ctx->multichannel_specified = false;
ctx->max_channels_specified = false;
ctx->max_channels = 1;
ctx->backupuid_specified = false; /* no backup intent for a user */

2
fs/smb/client/fs_context.h
View File

@@ -294,6 +294,8 @@ struct smb3_fs_context {
bool domainauto:1;
bool rdma:1;
bool multichannel:1;
bool multichannel_specified:1; /* true if user specified multichannel or nomultichannel */
bool max_channels_specified:1; /* true if user specified max_channels */
bool use_client_guid:1;
/* reuse existing guid for multichannel */
u8 client_guid[SMB2_CLIENT_GUID_SIZE];