From 6c12516083cf51b6e576691ac6e20c4a32f4edb9 Mon Sep 17 00:00:00 2001 From: Ryusuke Konishi Date: Mon, 28 Jun 2010 19:15:26 +0900 Subject: [PATCH] nilfs2: implement fallback for super root search Although nilfs redundantly uses two super blocks and each may point to different position on log, the current version of nilfs does not try fallback to the spare super block when it doesn't find any valid log at the position that the primary super block points to. This has been a cause of mount failures due to write order reversals on barrier less block devices. This inserts fallback code in error path of nilfs_search_super_root routine to resolve the mount failure problem. Signed-off-by: Ryusuke Konishi --- fs/nilfs2/the_nilfs.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 50 insertions(+), 2 deletions(-) diff --git a/fs/nilfs2/the_nilfs.c b/fs/nilfs2/the_nilfs.c index 0d2a46c..88c8976 100644 --- a/fs/nilfs2/the_nilfs.c +++ b/fs/nilfs2/the_nilfs.c @@ -38,6 +38,8 @@ static LIST_HEAD(nilfs_objects); static DEFINE_SPINLOCK(nilfs_lock); +static int nilfs_valid_sb(struct nilfs_super_block *sbp); + void nilfs_set_last_segment(struct the_nilfs *nilfs, sector_t start_blocknr, u64 seq, __u64 cno) { @@ -316,8 +318,50 @@ int load_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi) err = nilfs_search_super_root(nilfs, &ri); if (unlikely(err)) { - printk(KERN_ERR "NILFS: error searching super root.\n"); - goto failed; + struct nilfs_super_block **sbp = nilfs->ns_sbp; + int blocksize; + + if (err != -EINVAL) + goto scan_error; + + if (!nilfs_valid_sb(sbp[1])) { + printk(KERN_WARNING + "NILFS warning: unable to fall back to spare" + "super block\n"); + goto scan_error; + } + printk(KERN_INFO + "NILFS: try rollback from an earlier position\n"); + + /* + * restore super block with its spare and reconfigure + * relevant states of the nilfs object. + */ + memcpy(sbp[0], sbp[1], nilfs->ns_sbsize); + nilfs->ns_crc_seed = le32_to_cpu(sbp[0]->s_crc_seed); + nilfs->ns_sbwtime = le64_to_cpu(sbp[0]->s_wtime); + + /* verify consistency between two super blocks */ + blocksize = BLOCK_SIZE << le32_to_cpu(sbp[0]->s_log_block_size); + if (blocksize != nilfs->ns_blocksize) { + printk(KERN_WARNING + "NILFS warning: blocksize differs between " + "two super blocks (%d != %d)\n", + blocksize, nilfs->ns_blocksize); + goto scan_error; + } + + err = nilfs_store_log_cursor(nilfs, sbp[0]); + if (err) + goto scan_error; + + /* drop clean flag to allow roll-forward and recovery */ + nilfs->ns_mount_state &= ~NILFS_VALID_FS; + valid_fs = 0; + + err = nilfs_search_super_root(nilfs, &ri); + if (err) + goto scan_error; } err = nilfs_load_super_root(nilfs, ri.ri_super_root); @@ -371,6 +415,10 @@ int load_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi) sbi->s_super->s_flags = s_flags; return 0; + scan_error: + printk(KERN_ERR "NILFS: error searching super root.\n"); + goto failed; + failed_unload: nilfs_mdt_destroy(nilfs->ns_cpfile); nilfs_mdt_destroy(nilfs->ns_sufile); -- 2.7.4