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-rw-r--r--fs/cifs/connect.c33
1 files changed, 20 insertions, 13 deletions
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 19fdbda7aa95..c761935eab8c 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -2750,21 +2750,21 @@ void cifs_setup_cifs_sb(struct smb_vol *pvolume_info,
/*
* When the server supports very large writes via POSIX extensions, we can
- * allow up to 2^24 - PAGE_CACHE_SIZE.
+ * allow up to 2^24-1, minus the size of a WRITE_AND_X header, not including
+ * the RFC1001 length.
*
* 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.
+ * 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)
+#define CIFS_MAX_WSIZE ((1<<24) - 1 - sizeof(WRITE_REQ) + 4)
/*
- * 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.
+ * When the server doesn't allow large posix writes, only allow a wsize of
+ * 128k minus the size of the WRITE_AND_X header. That allows for a write up
+ * to the maximum size described by RFC1002.
*/
-#define CIFS_MAX_RFC1001_WSIZE (128 * 1024 - PAGE_CACHE_SIZE)
+#define CIFS_MAX_RFC1002_WSIZE (128 * 1024 - sizeof(WRITE_REQ) + 4)
/*
* The default wsize is 1M. find_get_pages seems to return a maximum of 256
@@ -2783,11 +2783,18 @@ cifs_negotiate_wsize(struct cifs_tcon *tcon, struct smb_vol *pvolume_info)
/* 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);
+ wsize = min_t(unsigned int, wsize, CIFS_MAX_RFC1002_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);
+ /*
+ * no CAP_LARGE_WRITE_X or is signing enabled without CAP_UNIX set?
+ * Limit it to max buffer offered by the server, minus the size of the
+ * WRITEX header, not including the 4 byte RFC1001 length.
+ */
+ if (!(server->capabilities & CAP_LARGE_WRITE_X) ||
+ (!(server->capabilities & CAP_UNIX) &&
+ (server->sec_mode & (SECMODE_SIGN_ENABLED|SECMODE_SIGN_REQUIRED))))
+ wsize = min_t(unsigned int, wsize,
+ server->maxBuf - sizeof(WRITE_REQ) + 4);
/* hard limit of CIFS_MAX_WSIZE */
wsize = min_t(unsigned int, wsize, CIFS_MAX_WSIZE);