logfs: handle powerfail on NAND flash
The write buffer may not have been written and may no longer be written
due to an interrupted write in the affected page.
Signed-off-by: Joern Engel <joern@logfs.org>
diff --git a/fs/logfs/dev_mtd.c b/fs/logfs/dev_mtd.c
index b02a402..a85d47d 100644
--- a/fs/logfs/dev_mtd.c
+++ b/fs/logfs/dev_mtd.c
@@ -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 @@
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 @@
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,
};