2011/5/20 Jeff Layton <jlayton@xxxxxxxxxx>:
> Now that we can handle larger wsizes in writepages, fix up the
> negotiation of the wsize to allow for that. find_get_pages only seems to
> give out a max of 256 pages at a time, so that gives us a reasonable
> default of 1M for the wsize.
>
> If the server however does not support large writes via POSIX
> extensions, then we cap the wsize to (128k - PAGE_CACHE_SIZE). That
> gives us a size that goes up to the max frame size specified in RFC1001.
>
> Finally, if CAP_LARGE_WRITE_AND_X isn't set, then further cap it to the
> largest size allowed by the protocol (USHRT_MAX).
>
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> ---
> fs/cifs/connect.c | 69 +++++++++++++++++++++++++++++++++++++---------------
> 1 files changed, 49 insertions(+), 20 deletions(-)
>
> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
> index ccb3ff8..490fb68 100644
> --- a/fs/cifs/connect.c
> +++ b/fs/cifs/connect.c
> @@ -2633,23 +2633,6 @@ static void setup_cifs_sb(struct smb_vol *pvolume_info,
> else /* default */
> cifs_sb->rsize = CIFSMaxBufSize;
>
> - if (pvolume_info->wsize > PAGEVEC_SIZE * PAGE_CACHE_SIZE) {
> - cERROR(1, "wsize %d too large, using 4096 instead",
> - pvolume_info->wsize);
> - cifs_sb->wsize = 4096;
> - } else if (pvolume_info->wsize)
> - cifs_sb->wsize = pvolume_info->wsize;
> - else
> - cifs_sb->wsize = min_t(const int,
> - PAGEVEC_SIZE * PAGE_CACHE_SIZE,
> - 127*1024);
> - /* old default of CIFSMaxBufSize was too small now
> - that SMB Write2 can send multiple pages in kvec.
> - RFC1001 does not describe what happens when frame
> - bigger than 128K is sent so use that as max in
> - conjunction with 52K kvec constraint on arch with 4K
> - page size */
> -
> if (cifs_sb->rsize < 2048) {
> cifs_sb->rsize = 2048;
> /* Windows ME may prefer this */
> @@ -2727,6 +2710,53 @@ static void setup_cifs_sb(struct smb_vol *pvolume_info,
> "mount option supported");
> }
>
> +/*
> + * When the server supports very large writes via POSIX extensions, we can
> + * allow up to 2^24 - PAGE_CACHE_SIZE.
> + *
> + * Note that this might make for "interesting" allocation problems during
> + * writeback however (as we have to allocate an array of pointers for the
> + * pages). A 16M write means ~32kb page array with PAGE_CACHE_SIZE == 4096.
> + */
> +#define CIFS_MAX_WSIZE ((1<<24) - PAGE_CACHE_SIZE)
> +
> +/*
> + * When the server doesn't allow large posix writes, default to a wsize of
> + * 128k - PAGE_CACHE_SIZE -- one page less than the largest frame size
> + * described in RFC1001. This allows space for the header without going over
> + * that by default.
> + */
> +#define CIFS_MAX_RFC1001_WSIZE (128 * 1024 - PAGE_CACHE_SIZE)
> +
> +/*
> + * The default wsize is 1M. find_get_pages seems to return a maximum of 256
> + * pages in a single call. With PAGE_CACHE_SIZE == 4k, this means we can fill
> + * a single wsize request with a single call.
> + */
> +#define CIFS_DEFAULT_WSIZE (1024 * 1024)
> +
> +static unsigned int
> +cifs_negotiate_wsize(struct cifsTconInfo *tcon, struct smb_vol *pvolume_info)
> +{
> + __u64 unix_cap = le64_to_cpu(tcon->fsUnixInfo.Capability);
> + struct TCP_Server_Info *server = tcon->ses->server;
> + unsigned int wsize = pvolume_info->wsize ? pvolume_info->wsize :
> + CIFS_DEFAULT_WSIZE;
> +
> + /* can server support 24-bit write sizes? (via UNIX extensions) */
> + if (!tcon->unix_ext || !(unix_cap & CIFS_UNIX_LARGE_WRITE_CAP))
> + wsize = min_t(unsigned int, wsize, CIFS_MAX_RFC1001_WSIZE);
> +
> + /* no CAP_LARGE_WRITE_X? Limit it to 16 bits */
> + if (!(server->capabilities & CAP_LARGE_WRITE_X))
> + wsize = min_t(unsigned int, wsize, USHRT_MAX);
> +
> + /* hard limit of CIFS_MAX_WSIZE */
> + wsize = min_t(unsigned int, wsize, CIFS_MAX_WSIZE);
> +
> + return wsize;
> +}
> +
> static int
> is_path_accessible(int xid, struct cifsTconInfo *tcon,
> struct cifs_sb_info *cifs_sb, const char *full_path)
> @@ -2988,13 +3018,12 @@ try_mount_again:
> cifs_sb->rsize = 1024 * 127;
> cFYI(DBG2, "no very large read support, rsize now 127K");
> }
> - if (!(tcon->ses->capabilities & CAP_LARGE_WRITE_X))
> - cifs_sb->wsize = min(cifs_sb->wsize,
> - (tcon->ses->server->maxBuf - MAX_CIFS_HDR_SIZE));
> if (!(tcon->ses->capabilities & CAP_LARGE_READ_X))
> cifs_sb->rsize = min(cifs_sb->rsize,
> (tcon->ses->server->maxBuf - MAX_CIFS_HDR_SIZE));
>
> + cifs_sb->wsize = cifs_negotiate_wsize(tcon, volume_info);
> +
> remote_path_check:
> #ifdef CONFIG_CIFS_DFS_UPCALL
> /*
> --
> 1.7.4.4
>
> --
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>
Reviewed-and-Tested-by: Pavel Shilovsky <piastry@xxxxxxxxxxx>
--
Best regards,
Pavel Shilovsky.
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