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cifs: clean up wsize negotiation and allow for larger wsize

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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@redhat.com>
Reviewed-and-Tested-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <sfrench@us.ibm.com>
This commit is contained in:
Jeff Layton 2011-05-19 16:22:58 -04:00 committed by Steve French
parent c3d17b63e5
commit f7910cbd9f
1 changed files with 49 additions and 20 deletions
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69
fs/cifs/connect.c
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@ -2647,23 +2647,6 @@ void cifs_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 */
@ -2742,6 +2725,53 @@ void cifs_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)
@ -3014,13 +3044,12 @@ 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
/*