From 6f485b41875dbf5160c1990322469c1f65f77b28 Mon Sep 17 00:00:00 2001 From: Joern Engel Date: Fri, 7 May 2010 19:38:40 +0200 Subject: [PATCH 1/1] 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 --- fs/logfs/dev_bdev.c | 6 ++++++ fs/logfs/dev_mtd.c | 24 +++++++++++++++++++++- fs/logfs/gc.c | 49 +++++++++++++++++++-------------------------- fs/logfs/logfs.h | 2 ++ 4 files changed, 52 insertions(+), 29 deletions(-) diff --git a/fs/logfs/dev_bdev.c b/fs/logfs/dev_bdev.c index 243c00071f76..9bd2ce2a3040 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 b02a4020241a..a85d47d13e4b 100644 --- a/fs/logfs/dev_mtd.c +++ b/fs/logfs/dev_mtd.c @@ -9,6 +9,7 @@ #include #include #include +#include #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 76c242fbe1b0..caa4419285dc 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 26a9458e6b13..93b55f337245 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); }; -- 2.34.1