From 074e427ba7f7398427e4f8e2aec071edcc509673 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Thu, 22 Jan 2015 09:10:33 +1100 Subject: [PATCH] xfs: sanitise sb_bad_features2 handling We currently have to ensure that every time we update sb_features2 that we update sb_bad_features2. Now that we log and format the superblock in it's entirety we actually don't have to care because we can simply update the sb_bad_features2 when we format it into the buffer. This removes the need for anything but the mount and superblock formatting code to care about sb_bad_features2, and hence removes the possibility that we forget to update bad_features2 when necessary in the future. Signed-off-by: Dave Chinner Reviewed-by: Brian Foster Signed-off-by: Dave Chinner --- fs/xfs/libxfs/xfs_format.h | 14 +++++++------- fs/xfs/libxfs/xfs_sb.c | 8 +++++++- fs/xfs/xfs_mount.c | 23 +++++++++++------------ 3 files changed, 25 insertions(+), 20 deletions(-) diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h index fbd6da263571..749c86102794 100644 --- a/fs/xfs/libxfs/xfs_format.h +++ b/fs/xfs/libxfs/xfs_format.h @@ -151,10 +151,13 @@ typedef struct xfs_sb { __uint32_t sb_features2; /* additional feature bits */ /* - * bad features2 field as a result of failing to pad the sb - * structure to 64 bits. Some machines will be using this field - * for features2 bits. Easiest just to mark it bad and not use - * it for anything else. + * bad features2 field as a result of failing to pad the sb structure to + * 64 bits. Some machines will be using this field for features2 bits. + * Easiest just to mark it bad and not use it for anything else. + * + * This is not kept up to date in memory; it is always overwritten by + * the value in sb_features2 when formatting the incore superblock to + * the disk buffer. */ __uint32_t sb_bad_features2; @@ -453,13 +456,11 @@ static inline void xfs_sb_version_addattr2(struct xfs_sb *sbp) { sbp->sb_versionnum |= XFS_SB_VERSION_MOREBITSBIT; sbp->sb_features2 |= XFS_SB_VERSION2_ATTR2BIT; - sbp->sb_bad_features2 |= XFS_SB_VERSION2_ATTR2BIT; } static inline void xfs_sb_version_removeattr2(struct xfs_sb *sbp) { sbp->sb_features2 &= ~XFS_SB_VERSION2_ATTR2BIT; - sbp->sb_bad_features2 &= ~XFS_SB_VERSION2_ATTR2BIT; if (!sbp->sb_features2) sbp->sb_versionnum &= ~XFS_SB_VERSION_MOREBITSBIT; } @@ -475,7 +476,6 @@ static inline void xfs_sb_version_addprojid32bit(struct xfs_sb *sbp) { sbp->sb_versionnum |= XFS_SB_VERSION_MOREBITSBIT; sbp->sb_features2 |= XFS_SB_VERSION2_PROJID32BIT; - sbp->sb_bad_features2 |= XFS_SB_VERSION2_PROJID32BIT; } /* diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c index 63f814872dfb..b0a5fe95a3e2 100644 --- a/fs/xfs/libxfs/xfs_sb.c +++ b/fs/xfs/libxfs/xfs_sb.c @@ -497,7 +497,6 @@ xfs_sb_to_disk( to->sb_fdblocks = cpu_to_be64(from->sb_fdblocks); to->sb_frextents = cpu_to_be64(from->sb_frextents); - to->sb_flags = from->sb_flags; to->sb_shared_vn = from->sb_shared_vn; to->sb_inoalignmt = cpu_to_be32(from->sb_inoalignmt); @@ -507,6 +506,13 @@ xfs_sb_to_disk( to->sb_logsectlog = from->sb_logsectlog; to->sb_logsectsize = cpu_to_be16(from->sb_logsectsize); to->sb_logsunit = cpu_to_be32(from->sb_logsunit); + + /* + * We need to ensure that bad_features2 always matches features2. + * Hence we enforce that here rather than having to remember to do it + * everywhere else that updates features2. + */ + from->sb_bad_features2 = from->sb_features2; to->sb_features2 = cpu_to_be32(from->sb_features2); to->sb_bad_features2 = cpu_to_be32(from->sb_bad_features2); diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c index 5ef9aa2bfa19..4fa80e63eea2 100644 --- a/fs/xfs/xfs_mount.c +++ b/fs/xfs/xfs_mount.c @@ -640,25 +640,24 @@ xfs_mountfs( xfs_sb_mount_common(mp, sbp); /* - * Check for a mismatched features2 values. Older kernels - * read & wrote into the wrong sb offset for sb_features2 - * on some platforms due to xfs_sb_t not being 64bit size aligned - * when sb_features2 was added, which made older superblock - * reading/writing routines swap it as a 64-bit value. + * Check for a mismatched features2 values. Older kernels read & wrote + * into the wrong sb offset for sb_features2 on some platforms due to + * xfs_sb_t not being 64bit size aligned when sb_features2 was added, + * which made older superblock reading/writing routines swap it as a + * 64-bit value. * * For backwards compatibility, we make both slots equal. * - * If we detect a mismatched field, we OR the set bits into the - * existing features2 field in case it has already been modified; we - * don't want to lose any features. We then update the bad location - * with the ORed value so that older kernels will see any features2 - * flags, and mark the two fields as needing updates once the - * transaction subsystem is online. + * If we detect a mismatched field, we OR the set bits into the existing + * features2 field in case it has already been modified; we don't want + * to lose any features. We then update the bad location with the ORed + * value so that older kernels will see any features2 flags. The + * superblock writeback code ensures the new sb_features2 is copied to + * sb_bad_features2 before it is logged or written to disk. */ if (xfs_sb_has_mismatched_features2(sbp)) { xfs_warn(mp, "correcting sb_features alignment problem"); sbp->sb_features2 |= sbp->sb_bad_features2; - sbp->sb_bad_features2 = sbp->sb_features2; mp->m_update_sb = true; /*