logfs: handle powerfail on NAND flash
[sfrench/cifs-2.6.git] / fs / logfs / dev_mtd.c
index b02a4020241ac653d7ffffc86c04a1e69d56ae3c..a85d47d13e4b04623dff3d873c66cc107b7f8599 100644 (file)
@@ -9,6 +9,7 @@
 #include <linux/completion.h>
 #include <linux/mount.h>
 #include <linux/sched.h>
+#include <linux/slab.h>
 
 #define PAGE_OFS(ofs) ((ofs) & (PAGE_SIZE-1))
 
@@ -126,7 +127,8 @@ static int mtd_readpage(void *_sb, struct page *page)
 
        err = mtd_read(sb, page->index << PAGE_SHIFT, PAGE_SIZE,
                        page_address(page));
-       if (err == -EUCLEAN) {
+       if (err == -EUCLEAN || err == -EBADMSG) {
+               /* -EBADMSG happens regularly on power failures */
                err = 0;
                /* FIXME: force GC this segment */
        }
@@ -233,12 +235,32 @@ static void mtd_put_device(struct super_block *sb)
        put_mtd_device(logfs_super(sb)->s_mtd);
 }
 
+static int mtd_can_write_buf(struct super_block *sb, u64 ofs)
+{
+       struct logfs_super *super = logfs_super(sb);
+       void *buf;
+       int err;
+
+       buf = kmalloc(super->s_writesize, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
+       err = mtd_read(sb, ofs, super->s_writesize, buf);
+       if (err)
+               goto out;
+       if (memchr_inv(buf, 0xff, super->s_writesize))
+               err = -EIO;
+       kfree(buf);
+out:
+       return err;
+}
+
 static const struct logfs_device_ops mtd_devops = {
        .find_first_sb  = mtd_find_first_sb,
        .find_last_sb   = mtd_find_last_sb,
        .readpage       = mtd_readpage,
        .writeseg       = mtd_writeseg,
        .erase          = mtd_erase,
+       .can_write_buf  = mtd_can_write_buf,
        .sync           = mtd_sync,
        .put_device     = mtd_put_device,
 };