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authorJoern Engel <joern@logfs.org>2010-05-07 19:38:40 +0200
committerJoern Engel <joern@logfs.org>2010-05-07 19:38:40 +0200
commit6f485b41875dbf5160c1990322469c1f65f77b28 (patch)
tree9912cee9517b57c2cb3c0318861f2a9eeb4139b2 /fs/logfs
parentccf31c10f125ab5233c8517f91d4b3bd0bd60936 (diff)
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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>
Diffstat (limited to 'fs/logfs')
-rw-r--r--fs/logfs/dev_bdev.c6
-rw-r--r--fs/logfs/dev_mtd.c24
-rw-r--r--fs/logfs/gc.c49
-rw-r--r--fs/logfs/logfs.h2
4 files changed, 52 insertions, 29 deletions
diff --git a/fs/logfs/dev_bdev.c b/fs/logfs/dev_bdev.c
index 243c000..9bd2ce2 100644
--- a/fs/logfs/dev_bdev.c
+++ b/fs/logfs/dev_bdev.c
@@ -303,6 +303,11 @@ static void bdev_put_device(struct super_block *sb)
close_bdev_exclusive(logfs_super(sb)->s_bdev, FMODE_READ|FMODE_WRITE);
}
+static int bdev_can_write_buf(struct super_block *sb, u64 ofs)
+{
+ return 0;
+}
+
static const struct logfs_device_ops bd_devops = {
.find_first_sb = bdev_find_first_sb,
.find_last_sb = bdev_find_last_sb,
@@ -310,6 +315,7 @@ static const struct logfs_device_ops bd_devops = {
.readpage = bdev_readpage,
.writeseg = bdev_writeseg,
.erase = bdev_erase,
+ .can_write_buf = bdev_can_write_buf,
.sync = bdev_sync,
.put_device = bdev_put_device,
};
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 @@ 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,
};
diff --git a/fs/logfs/gc.c b/fs/logfs/gc.c
index 76c242f..caa4419 100644
--- a/fs/logfs/gc.c
+++ b/fs/logfs/gc.c
@@ -122,7 +122,7 @@ static void logfs_cleanse_block(struct super_block *sb, u64 ofs, u64 ino,
logfs_safe_iput(inode, cookie);
}
-static u32 logfs_gc_segment(struct super_block *sb, u32 segno, u8 dist)
+static u32 logfs_gc_segment(struct super_block *sb, u32 segno)
{
struct logfs_super *super = logfs_super(sb);
struct logfs_segment_header sh;
@@ -401,7 +401,7 @@ static int __logfs_gc_once(struct super_block *sb, struct gc_candidate *cand)
segno, (u64)segno << super->s_segshift,
dist, no_free_segments(sb), valid,
super->s_free_bytes);
- cleaned = logfs_gc_segment(sb, segno, dist);
+ cleaned = logfs_gc_segment(sb, segno);
log_gc("GC segment #%02x complete - now %x valid\n", segno,
valid - cleaned);
BUG_ON(cleaned != valid);
@@ -632,38 +632,31 @@ static int check_area(struct super_block *sb, int i)
{
struct logfs_super *super = logfs_super(sb);
struct logfs_area *area = super->s_area[i];
- struct logfs_object_header oh;
+ gc_level_t gc_level;
+ u32 cleaned, valid, ec;
u32 segno = area->a_segno;
- u32 ofs = area->a_used_bytes;
- __be32 crc;
- int err;
+ u64 ofs = dev_ofs(sb, area->a_segno, area->a_written_bytes);
if (!area->a_is_open)
return 0;
- for (ofs = area->a_used_bytes;
- ofs <= super->s_segsize - sizeof(oh);
- ofs += (u32)be16_to_cpu(oh.len) + sizeof(oh)) {
- err = wbuf_read(sb, dev_ofs(sb, segno, ofs), sizeof(oh), &oh);
- if (err)
- return err;
-
- if (!memchr_inv(&oh, 0xff, sizeof(oh)))
- break;
+ if (super->s_devops->can_write_buf(sb, ofs) == 0)
+ return 0;
- crc = logfs_crc32(&oh, sizeof(oh) - 4, 4);
- if (crc != oh.crc) {
- printk(KERN_INFO "interrupted header at %llx\n",
- dev_ofs(sb, segno, ofs));
- return 0;
- }
- }
- if (ofs != area->a_used_bytes) {
- printk(KERN_INFO "%x bytes unaccounted data found at %llx\n",
- ofs - area->a_used_bytes,
- dev_ofs(sb, segno, area->a_used_bytes));
- area->a_used_bytes = ofs;
- }
+ printk(KERN_INFO"LogFS: Possibly incomplete write at %llx\n", ofs);
+ /*
+ * The device cannot write back the write buffer. Most likely the
+ * wbuf was already written out and the system crashed at some point
+ * before the journal commit happened. In that case we wouldn't have
+ * to do anything. But if the crash happened before the wbuf was
+ * written out correctly, we must GC this segment. So assume the
+ * worst and always do the GC run.
+ */
+ area->a_is_open = 0;
+ valid = logfs_valid_bytes(sb, segno, &ec, &gc_level);
+ cleaned = logfs_gc_segment(sb, segno);
+ if (cleaned != valid)
+ return -EIO;
return 0;
}
diff --git a/fs/logfs/logfs.h b/fs/logfs/logfs.h
index 26a9458..93b55f3 100644
--- a/fs/logfs/logfs.h
+++ b/fs/logfs/logfs.h
@@ -144,6 +144,7 @@ struct logfs_area_ops {
* @erase: erase one segment
* @read: read from the device
* @erase: erase part of the device
+ * @can_write_buf: decide whether wbuf can be written to ofs
*/
struct logfs_device_ops {
struct page *(*find_first_sb)(struct super_block *sb, u64 *ofs);
@@ -153,6 +154,7 @@ struct logfs_device_ops {
void (*writeseg)(struct super_block *sb, u64 ofs, size_t len);
int (*erase)(struct super_block *sb, loff_t ofs, size_t len,
int ensure_write);
+ int (*can_write_buf)(struct super_block *sb, u64 ofs);
void (*sync)(struct super_block *sb);
void (*put_device)(struct super_block *sb);
};