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author | Jeff Layton <jlayton@redhat.com> | 2012-07-11 13:09:35 (GMT) |
---|---|---|
committer | Steve French <smfrench@gmail.com> | 2012-07-17 04:57:09 (GMT) |
commit | 3ae629d98bd5ed77585a878566f04f310adbc591 (patch) | |
tree | 11a55d0bdca06f3a8d0b37df19e668a400c7a62c | |
parent | ffc61ccbb96809df8d97ed609ac86b509eaf9056 (diff) | |
download | linux-fsl-qoriq-3ae629d98bd5ed77585a878566f04f310adbc591.tar.xz |
cifs: on CONFIG_HIGHMEM machines, limit the rsize/wsize to the kmap space
We currently rely on being able to kmap all of the pages in an async
read or write request. If you're on a machine that has CONFIG_HIGHMEM
set then that kmap space is limited, sometimes to as low as 512 slots.
With 512 slots, we can only support up to a 2M r/wsize, and that's
assuming that we can get our greedy little hands on all of them. There
are other users however, so it's possible we'll end up stuck with a
size that large.
Since we can't handle a rsize or wsize larger than that currently, cap
those options at the number of kmap slots we have. We could consider
capping it even lower, but we currently default to a max of 1M. Might as
well allow those luddites on 32 bit arches enough rope to hang
themselves.
A more robust fix would be to teach the send and receive routines how
to contend with an array of pages so we don't need to marshal up a kvec
array at all. That's a fairly significant overhaul though, so we'll need
this limit in place until that's ready.
Cc: <stable@vger.kernel.org>
Reported-by: Jian Li <jiali@redhat.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
-rw-r--r-- | fs/cifs/connect.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index 0ae86dd..94b7788 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -3445,6 +3445,18 @@ void cifs_setup_cifs_sb(struct smb_vol *pvolume_info, #define CIFS_DEFAULT_NON_POSIX_RSIZE (60 * 1024) #define CIFS_DEFAULT_NON_POSIX_WSIZE (65536) +/* + * On hosts with high memory, we can't currently support wsize/rsize that are + * larger than we can kmap at once. Cap the rsize/wsize at + * LAST_PKMAP * PAGE_SIZE. We'll never be able to fill a read or write request + * larger than that anyway. + */ +#ifdef CONFIG_HIGHMEM +#define CIFS_KMAP_SIZE_LIMIT (LAST_PKMAP * PAGE_CACHE_SIZE) +#else /* CONFIG_HIGHMEM */ +#define CIFS_KMAP_SIZE_LIMIT (1<<24) +#endif /* CONFIG_HIGHMEM */ + static unsigned int cifs_negotiate_wsize(struct cifs_tcon *tcon, struct smb_vol *pvolume_info) { @@ -3475,6 +3487,9 @@ cifs_negotiate_wsize(struct cifs_tcon *tcon, struct smb_vol *pvolume_info) wsize = min_t(unsigned int, wsize, server->maxBuf - sizeof(WRITE_REQ) + 4); + /* limit to the amount that we can kmap at once */ + wsize = min_t(unsigned int, wsize, CIFS_KMAP_SIZE_LIMIT); + /* hard limit of CIFS_MAX_WSIZE */ wsize = min_t(unsigned int, wsize, CIFS_MAX_WSIZE); @@ -3516,6 +3531,9 @@ cifs_negotiate_rsize(struct cifs_tcon *tcon, struct smb_vol *pvolume_info) if (!(server->capabilities & CAP_LARGE_READ_X)) rsize = min_t(unsigned int, CIFSMaxBufSize, rsize); + /* limit to the amount that we can kmap at once */ + rsize = min_t(unsigned int, rsize, CIFS_KMAP_SIZE_LIMIT); + /* hard limit of CIFS_MAX_RSIZE */ rsize = min_t(unsigned int, rsize, CIFS_MAX_RSIZE); |