6.6-stable review patch. If anyone has any objections, please let me know.
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From: Steve French stfrench@microsoft.com
commit 4860abb91f3d7fbaf8147d54782149bb1fc45892 upstream.
The conversion to netfs in the 6.3 kernel caused a regression when maximum write size is set by the server to an unexpected value which is not a multiple of 4096 (similarly if the user overrides the maximum write size by setting mount parm "wsize", but sets it to a value that is not a multiple of 4096). When negotiated write size is not a multiple of 4096 the netfs code can skip the end of the final page when doing large sequential writes, causing data corruption.
This section of code is being rewritten/removed due to a large netfs change, but until that point (ie for the 6.3 kernel until now) we can not support non-standard maximum write sizes.
Add a warning if a user specifies a wsize on mount that is not a multiple of 4096 (and round down), also add a change where we round down the maximum write size if the server negotiates a value that is not a multiple of 4096 (we also have to check to make sure that we do not round it down to zero).
Reported-by: "R. Diez" rdiez-2006@rd10.de Fixes: d08089f649a0 ("cifs: Change the I/O paths to use an iterator rather than a page list") Suggested-by: Ronnie Sahlberg ronniesahlberg@gmail.com Acked-by: Ronnie Sahlberg ronniesahlberg@gmail.com Tested-by: Matthew Ruffell matthew.ruffell@canonical.com Reviewed-by: Shyam Prasad N sprasad@microsoft.com Cc: stable@vger.kernel.org # v6.3+ Cc: David Howells dhowells@redhat.com Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/smb/client/connect.c | 14 ++++++++++++-- fs/smb/client/fs_context.c | 11 +++++++++++ 2 files changed, 23 insertions(+), 2 deletions(-)
--- a/fs/smb/client/connect.c +++ b/fs/smb/client/connect.c @@ -3426,8 +3426,18 @@ int cifs_mount_get_tcon(struct cifs_moun * the user on mount */ if ((cifs_sb->ctx->wsize == 0) || - (cifs_sb->ctx->wsize > server->ops->negotiate_wsize(tcon, ctx))) - cifs_sb->ctx->wsize = server->ops->negotiate_wsize(tcon, ctx); + (cifs_sb->ctx->wsize > server->ops->negotiate_wsize(tcon, ctx))) { + cifs_sb->ctx->wsize = + round_down(server->ops->negotiate_wsize(tcon, ctx), PAGE_SIZE); + /* + * in the very unlikely event that the server sent a max write size under PAGE_SIZE, + * (which would get rounded down to 0) then reset wsize to absolute minimum eg 4096 + */ + if (cifs_sb->ctx->wsize == 0) { + cifs_sb->ctx->wsize = PAGE_SIZE; + cifs_dbg(VFS, "wsize too small, reset to minimum ie PAGE_SIZE, usually 4096\n"); + } + } if ((cifs_sb->ctx->rsize == 0) || (cifs_sb->ctx->rsize > server->ops->negotiate_rsize(tcon, ctx))) cifs_sb->ctx->rsize = server->ops->negotiate_rsize(tcon, ctx); --- a/fs/smb/client/fs_context.c +++ b/fs/smb/client/fs_context.c @@ -1107,6 +1107,17 @@ static int smb3_fs_context_parse_param(s case Opt_wsize: ctx->wsize = result.uint_32; ctx->got_wsize = true; + if (ctx->wsize % PAGE_SIZE != 0) { + ctx->wsize = round_down(ctx->wsize, PAGE_SIZE); + if (ctx->wsize == 0) { + ctx->wsize = PAGE_SIZE; + cifs_dbg(VFS, "wsize too small, reset to minimum %ld\n", PAGE_SIZE); + } else { + cifs_dbg(VFS, + "wsize rounded down to %d to multiple of PAGE_SIZE %ld\n", + ctx->wsize, PAGE_SIZE); + } + } break; case Opt_acregmax: ctx->acregmax = HZ * result.uint_32;