From b39f0de23d8f22253d441b3b68414e9a1d027cf6 Mon Sep 17 00:00:00 2001 From: Yunlei He Date: Tue, 15 Dec 2015 17:17:20 +0800 Subject: [PATCH] f2fs: backup raw_super in sbi f2fs use fields of f2fs_super_block struct directly in a grabbed buffer. Once the buffer happen to be destroyed (e.g. through dd), it may bring in unpredictable effect on f2fs. This patch fixes to allocate additional buffer to store datas of super block rather than using grabbed block buffer directly. Signed-off-by: Yunlei He Signed-off-by: Jaegeuk Kim Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim --- fs/f2fs/super.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index 4031f8ed9d24..6dfe0d32ad88 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -568,6 +568,7 @@ static void f2fs_put_super(struct super_block *sb) sb->s_fs_info = NULL; brelse(sbi->raw_super_buf); + kfree(sbi->raw_super); kfree(sbi); } @@ -1139,6 +1140,9 @@ static int read_raw_super_block(struct super_block *sb, struct f2fs_super_block *super; int err = 0; + super = kzalloc(sizeof(struct f2fs_super_block), GFP_KERNEL); + if (!super) + return -ENOMEM; retry: buffer = sb_bread(sb, block); if (!buffer) { @@ -1154,8 +1158,7 @@ retry: } } - super = (struct f2fs_super_block *) - ((char *)(buffer)->b_data + F2FS_SUPER_OFFSET); + memcpy(super, buffer->b_data + F2FS_SUPER_OFFSET, sizeof(*super)); /* sanity checking of raw super */ if (sanity_check_raw_super(sb, super)) { @@ -1189,14 +1192,17 @@ retry: out: /* No valid superblock */ - if (!*raw_super) + if (!*raw_super) { + kfree(super); return err; + } return 0; } int f2fs_commit_super(struct f2fs_sb_info *sbi, bool recover) { + struct f2fs_super_block *super = F2FS_RAW_SUPER(sbi); struct buffer_head *sbh = sbi->raw_super_buf; struct buffer_head *bh; int err; @@ -1207,7 +1213,7 @@ int f2fs_commit_super(struct f2fs_sb_info *sbi, bool recover) return -EIO; lock_buffer(bh); - memcpy(bh->b_data, sbh->b_data, sbh->b_size); + memcpy(bh->b_data + F2FS_SUPER_OFFSET, super, sizeof(*super)); WARN_ON(sbh->b_size != F2FS_BLKSIZE); set_buffer_uptodate(bh); set_buffer_dirty(bh); @@ -1223,6 +1229,10 @@ int f2fs_commit_super(struct f2fs_sb_info *sbi, bool recover) /* write current valid superblock */ lock_buffer(sbh); + if (memcmp(sbh->b_data + F2FS_SUPER_OFFSET, super, sizeof(*super))) { + f2fs_msg(sbi->sb, KERN_INFO, "Write modified valid superblock"); + memcpy(sbh->b_data + F2FS_SUPER_OFFSET, super, sizeof(*super)); + } set_buffer_dirty(sbh); unlock_buffer(sbh); @@ -1497,6 +1507,7 @@ free_options: kfree(options); free_sb_buf: brelse(raw_super_buf); + kfree(raw_super); free_sbi: kfree(sbi); -- 2.20.1