2 files changed, 26 insertions, 0 deletions

diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
index 6174a97d7902..c66902df3171 100644
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -151,6 +151,20 @@ static int part_write (struct mtd_info *mtd, loff_t to, size_t len,
                                     len, retlen, buf);
 }
 
+static int part_panic_write (struct mtd_info *mtd, loff_t to, size_t len,
+                        size_t *retlen, const u_char *buf)
+{
+        struct mtd_part *part = PART(mtd);
+        if (!(mtd->flags & MTD_WRITEABLE))
+                return -EROFS;
+        if (to >= mtd->size)
+                len = 0;
+        else if (to + len > mtd->size)
+                len = mtd->size - to;
+        return part->master->panic_write (part->master, to + part->offset,
+                                    len, retlen, buf);
+}
+
 static int part_write_oob(struct mtd_info *mtd, loff_t to,
                          struct mtd_oob_ops *ops)
 {
@@ -352,6 +366,9 @@ int add_mtd_partitions(struct mtd_info *master,
                 slave->mtd.read = part_read;
                 slave->mtd.write = part_write;
 
+                if (master->panic_write)
+                        slave->mtd.panic_write = part_panic_write;
+
                 if(master->point && master->unpoint){
                         slave->mtd.point = part_point;
                         slave->mtd.unpoint = part_unpoint;
diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
index 783fc983417c..0a13bb35f044 100644
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -152,6 +152,15 @@ struct mtd_info {
         int (*read) (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf);
         int (*write) (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf);
 
+        /* In blackbox flight recorder like scenarios we want to make successful
+           writes in interrupt context. panic_write() is only intended to be
+           called when its known the kernel is about to panic and we need the
+           write to succeed. Since the kernel is not going to be running for much
+           longer, this function can break locks and delay to ensure the write
+           succeeds (but not sleep). */
+
+        int (*panic_write) (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf);
+
         int (*read_oob) (struct mtd_info *mtd, loff_t from,
                          struct mtd_oob_ops *ops);
         int (*write_oob) (struct mtd_info *mtd, loff_t to,