From 0388b9459eb4752072e4b3b61e809d3678f0bf45 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Thu, 19 May 2011 16:22:58 -0400 Subject: [PATCH] cifs: clean up wsize negotiation and allow for larger wsize commit f7910cbd9fa319ee4501074f1f3b5ce23c4b1518 upstream. 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 Reviewed-and-Tested-by: Pavel Shilovsky Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman --- fs/cifs/connect.c | 69 +++++++++++++++++++++++++++++++++-------------- 1 file changed, 49 insertions(+), 20 deletions(-) diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index 523658214c02..02538a5e7608 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -2571,23 +2571,6 @@ 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 */ @@ -2665,6 +2648,53 @@ 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) @@ -2866,13 +2896,12 @@ 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: /* check if a whole path (including prepath) is not remote */ if (!rc && tcon) { -- 2.39.5