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author | Steve French <stfrench@microsoft.com> | 2018-08-10 02:25:06 -0500 |
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committer | Steve French <stfrench@microsoft.com> | 2018-08-10 11:54:08 -0500 |
commit | cdeaf9d04a5a0f51220d2f025385c553220bfb5c (patch) | |
tree | 5527e70a8b44353df8ebc37a66628b288a9af9aa /fs/cifs/smb2pdu.c | |
parent | e55954a5f7ce0e321cea9f91f4ebeb2a4e0165f4 (diff) | |
download | linux-stable-cdeaf9d04a5a0f51220d2f025385c553220bfb5c.tar.gz linux-stable-cdeaf9d04a5a0f51220d2f025385c553220bfb5c.tar.bz2 linux-stable-cdeaf9d04a5a0f51220d2f025385c553220bfb5c.zip |
smb3: allow previous versions to be mounted with snapshot= mount parm
mounting with the "snapshots=" mount parm allows a read-only
view of a previous version of a file system (see MS-SMB2
and "timewarp" tokens, section 2.2.13.2.6) based on the timestamp
passed in on the snapshots mount parm.
Add processing to optionally send this create context.
Example output:
/mnt1 is mounted with "snapshots=..." and will see an earlier
version of the directory, with three fewer files than /mnt2
the current version of the directory.
root@Ubuntu-17-Virtual-Machine:~/cifs-2.6# cat /proc/mounts | grep cifs
//172.22.149.186/public /mnt1 cifs
ro,relatime,vers=default,cache=strict,username=smfrench,uid=0,noforceuid,gid=0,noforcegid,addr=172.22.149.186,file_mode=0755,dir_mode=0755,soft,nounix,mapposix,rsize=1048576,wsize=1048576,echo_interval=60,snapshot=131748608570000000,actimeo=1
//172.22.149.186/public /mnt2 cifs
rw,relatime,vers=default,cache=strict,username=smfrench,uid=0,noforceuid,gid=0,noforcegid,addr=172.22.149.186,file_mode=0755,dir_mode=0755,soft,nounix,mapposix,rsize=1048576,wsize=1048576,echo_interval=60,actimeo=1
root@Ubuntu-17-Virtual-Machine:~/cifs-2.6# ls /mnt1
EmptyDir newerdir
root@Ubuntu-17-Virtual-Machine:~/cifs-2.6# ls /mnt1/newerdir
root@Ubuntu-17-Virtual-Machine:~/cifs-2.6# ls /mnt2
EmptyDir file newerdir newestdir timestamp-trace.cap
root@Ubuntu-17-Virtual-Machine:~/cifs-2.6# ls /mnt2/newerdir
new-file-not-in-snapshot
Snapshots are extremely useful for comparing previous versions of files or directories,
and recovering from data corruptions or mistakes.
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Diffstat (limited to 'fs/cifs/smb2pdu.c')
-rw-r--r-- | fs/cifs/smb2pdu.c | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c index faf2b779e5cb..2f1938011395 100644 --- a/fs/cifs/smb2pdu.c +++ b/fs/cifs/smb2pdu.c @@ -1856,6 +1856,51 @@ add_durable_context(struct kvec *iov, unsigned int *num_iovec, return 0; } +/* See MS-SMB2 2.2.13.2.7 */ +static struct crt_twarp_ctxt * +create_twarp_buf(__u64 timewarp) +{ + struct crt_twarp_ctxt *buf; + + buf = kzalloc(sizeof(struct crt_twarp_ctxt), GFP_KERNEL); + if (!buf) + return NULL; + + buf->ccontext.DataOffset = cpu_to_le16(offsetof + (struct crt_twarp_ctxt, Timestamp)); + buf->ccontext.DataLength = cpu_to_le32(8); + buf->ccontext.NameOffset = cpu_to_le16(offsetof + (struct crt_twarp_ctxt, Name)); + buf->ccontext.NameLength = cpu_to_le16(4); + /* SMB2_CREATE_TIMEWARP_TOKEN is "TWrp" */ + buf->Name[0] = 'T'; + buf->Name[1] = 'W'; + buf->Name[2] = 'r'; + buf->Name[3] = 'p'; + buf->Timestamp = cpu_to_le64(timewarp); + return buf; +} + +/* See MS-SMB2 2.2.13.2.7 */ +static int +add_twarp_context(struct kvec *iov, unsigned int *num_iovec, __u64 timewarp) +{ + struct smb2_create_req *req = iov[0].iov_base; + unsigned int num = *num_iovec; + + iov[num].iov_base = create_twarp_buf(timewarp); + if (iov[num].iov_base == NULL) + return -ENOMEM; + iov[num].iov_len = sizeof(struct crt_twarp_ctxt); + if (!req->CreateContextsOffset) + req->CreateContextsOffset = cpu_to_le32( + sizeof(struct smb2_create_req) + + iov[num - 1].iov_len); + le32_add_cpu(&req->CreateContextsLength, sizeof(struct crt_twarp_ctxt)); + *num_iovec = num + 1; + return 0; +} + static int alloc_path_with_tree_prefix(__le16 **out_path, int *out_size, int *out_len, const char *treename, const __le16 *path) @@ -2168,6 +2213,21 @@ SMB2_open_init(struct cifs_tcon *tcon, struct smb_rqst *rqst, __u8 *oplock, return rc; } + if (tcon->snapshot_time) { + cifs_dbg(FYI, "adding snapshot context\n"); + if (n_iov > 2) { + struct create_context *ccontext = + (struct create_context *)iov[n_iov-1].iov_base; + ccontext->Next = + cpu_to_le32(iov[n_iov-1].iov_len); + } + + rc = add_twarp_context(iov, &n_iov, tcon->snapshot_time); + if (rc) + return rc; + } + + rqst->rq_nvec = n_iov; return 0; } |