diff options
Diffstat (limited to 'fs/cifs/cifssmb.c')
| -rw-r--r-- | fs/cifs/cifssmb.c | 30 |
1 files changed, 29 insertions, 1 deletions
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c index 5b400730c21..4ee522b3f66 100644 --- a/fs/cifs/cifssmb.c +++ b/fs/cifs/cifssmb.c @@ -86,7 +86,31 @@ static struct { #endif /* CONFIG_CIFS_WEAK_PW_HASH */ #endif /* CIFS_POSIX */ -/* Forward declarations */ +#ifdef CONFIG_HIGHMEM +/* + * On arches that have high memory, kmap address space is limited. By + * serializing the kmap operations on those arches, we ensure that we don't + * end up with a bunch of threads in writeback with partially mapped page + * arrays, stuck waiting for kmap to come back. That situation prevents + * progress and can deadlock. + */ +static DEFINE_MUTEX(cifs_kmap_mutex); + +static inline void +cifs_kmap_lock(void) +{ + mutex_lock(&cifs_kmap_mutex); +} + +static inline void +cifs_kmap_unlock(void) +{ + mutex_unlock(&cifs_kmap_mutex); +} +#else /* !CONFIG_HIGHMEM */ +#define cifs_kmap_lock() do { ; } while(0) +#define cifs_kmap_unlock() do { ; } while(0) +#endif /* CONFIG_HIGHMEM */ /* Mark as invalid, all open files on tree connections since they were closed when session to server was lost */ @@ -1503,7 +1527,9 @@ cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid) } /* marshal up the page array */ + cifs_kmap_lock(); len = rdata->marshal_iov(rdata, data_len); + cifs_kmap_unlock(); data_len -= len; /* issue the read if we have any iovecs left to fill */ @@ -2069,7 +2095,9 @@ cifs_async_writev(struct cifs_writedata *wdata) * and set the iov_len properly for each one. It may also set * wdata->bytes too. */ + cifs_kmap_lock(); wdata->marshal_iov(iov, wdata); + cifs_kmap_unlock(); cFYI(1, "async write at %llu %u bytes", wdata->offset, wdata->bytes); |