David Chinner wrote:
> There is a bug in mkfs.xfs that can result in writing the features2
> field in the superblock to the wrong location. This only occurs
> on some architectures, typically those with 32 bit userspace and
> 64 bit kernels.
>
> This patch detects the defect at mount time, logs a warning
> such as:
>
> XFS: correcting sb_features alignment problem
>
> in dmesg and corrects the problem so that everything is OK.
> it also blacklists the bad field in the superblock so it does
> not get used for something else later on.
Looks good to me, thanks for fixing it up properly.
You can add Reviewed-by: or Acked-by: or whatever is appropriate...
Eric Sandeen <sandeen@xxxxxxxxxxx>
Thanks,
-Eric
> Signed-off-by: Dave Chinner <dgc@xxxxxxx>
> ---
> fs/xfs/xfs_mount.c | 34 ++++++++++++++++++++++++++++------
> fs/xfs/xfs_sb.h | 37 ++++++++++++++++++++++++++++++++++---
> 2 files changed, 62 insertions(+), 9 deletions(-)
>
> Index: 2.6.x-xfs-new/fs/xfs/xfs_mount.c
> ===================================================================
> --- 2.6.x-xfs-new.orig/fs/xfs/xfs_mount.c 2007-11-22 10:25:25.590278381
> +1100
> +++ 2.6.x-xfs-new/fs/xfs/xfs_mount.c 2007-11-22 10:31:27.891999961 +1100
> @@ -44,7 +44,7 @@
> #include "xfs_quota.h"
> #include "xfs_fsops.h"
>
> -STATIC void xfs_mount_log_sbunit(xfs_mount_t *, __int64_t);
> +STATIC void xfs_mount_log_sb(xfs_mount_t *, __int64_t);
> STATIC int xfs_uuid_mount(xfs_mount_t *);
> STATIC void xfs_uuid_unmount(xfs_mount_t *mp);
> STATIC void xfs_unmountfs_wait(xfs_mount_t *);
> @@ -119,6 +119,7 @@ static const struct {
> { offsetof(xfs_sb_t, sb_logsectsize),0 },
> { offsetof(xfs_sb_t, sb_logsunit), 0 },
> { offsetof(xfs_sb_t, sb_features2), 0 },
> + { offsetof(xfs_sb_t, sb_bad_features2), 0 },
> { sizeof(xfs_sb_t), 0 }
> };
>
> @@ -455,6 +456,7 @@ xfs_sb_from_disk(
> to->sb_logsectsize = be16_to_cpu(from->sb_logsectsize);
> to->sb_logsunit = be32_to_cpu(from->sb_logsunit);
> to->sb_features2 = be32_to_cpu(from->sb_features2);
> + to->sb_bad_features2 = be32_to_cpu(from->sb_bad_features2);
> }
>
> /*
> @@ -976,6 +978,26 @@ xfs_mountfs(
> xfs_mount_common(mp, sbp);
>
> /*
> + * Check for a bad features2 field alignment. This happened on
> + * some platforms due to xfs_sb_t not being 64bit size aligned
> + * when sb_features was added and hence the compiler put it in
> + * the wrong place.
> + *
> + * If we detect a bad field, we or the set bits into the existing
> + * features2 field in case it has already been modified and we
> + * don't want to lose any features. Zero the bad one and mark
> + * the two fields as needing updates once the transaction subsystem
> + * is online.
> + */
> + if (xfs_sb_has_bad_features2(sbp)) {
> + cmn_err(CE_WARN,
> + "XFS: correcting sb_features alignment problem");
> + sbp->sb_features2 |= sbp->sb_bad_features2;
> + sbp->sb_bad_features2 = 0;
> + update_flags |= XFS_SB_FEATURES2 | XFS_SB_BAD_FEATURES2;
> + }
> +
> + /*
> * Check if sb_agblocks is aligned at stripe boundary
> * If sb_agblocks is NOT aligned turn off m_dalign since
> * allocator alignment is within an ag, therefore ag has
> @@ -1165,11 +1187,10 @@ xfs_mountfs(
> }
>
> /*
> - * If fs is not mounted readonly, then update the superblock
> - * unit and width changes.
> + * If fs is not mounted readonly, then update the superblock changes.
> */
> if (update_flags && !(mp->m_flags & XFS_MOUNT_RDONLY))
> - xfs_mount_log_sbunit(mp, update_flags);
> + xfs_mount_log_sb(mp, update_flags);
>
> /*
> * Initialise the XFS quota management subsystem for this mount
> @@ -1884,13 +1905,14 @@ xfs_uuid_unmount(
> * be altered by the mount options. Only the first superblock is updated.
> */
> STATIC void
> -xfs_mount_log_sbunit(
> +xfs_mount_log_sb(
> xfs_mount_t *mp,
> __int64_t fields)
> {
> xfs_trans_t *tp;
>
> - ASSERT(fields & (XFS_SB_UNIT|XFS_SB_WIDTH|XFS_SB_UUID));
> + ASSERT(fields & (XFS_SB_UNIT | XFS_SB_WIDTH | XFS_SB_UUID |
> + XFS_SB_FEATURES2 | XFS_SB_BAD_FEATURES2));
>
> tp = xfs_trans_alloc(mp, XFS_TRANS_SB_UNIT);
> if (xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
> Index: 2.6.x-xfs-new/fs/xfs/xfs_sb.h
> ===================================================================
> --- 2.6.x-xfs-new.orig/fs/xfs/xfs_sb.h 2007-11-22 10:25:25.598277360
> +1100
> +++ 2.6.x-xfs-new/fs/xfs/xfs_sb.h 2007-11-22 10:31:27.891999961 +1100
> @@ -89,6 +89,7 @@ struct xfs_mount;
>
> /*
> * Superblock - in core version. Must match the ondisk version below.
> + * Must be padded to 64 bit alignment.
> */
> typedef struct xfs_sb {
> __uint32_t sb_magicnum; /* magic number == XFS_SB_MAGIC */
> @@ -145,10 +146,21 @@ typedef struct xfs_sb {
> __uint16_t sb_logsectsize; /* sector size for the log, bytes */
> __uint32_t sb_logsunit; /* stripe unit size for the log */
> __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.
> + */
> + __uint32_t sb_bad_features2;
> +
> + /* must be padded to 64 bit alignment */
> } xfs_sb_t;
>
> /*
> - * Superblock - on disk version. Must match the in core version below.
> + * Superblock - on disk version. Must match the in core version above.
> + * Must be padded to 64 bit alignment.
> */
> typedef struct xfs_dsb {
> __be32 sb_magicnum; /* magic number == XFS_SB_MAGIC */
> @@ -205,6 +217,15 @@ typedef struct xfs_dsb {
> __be16 sb_logsectsize; /* sector size for the log, bytes */
> __be32 sb_logsunit; /* stripe unit size for the log */
> __be32 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.
> + */
> + __be32 sb_bad_features2;
> +
> + /* must be padded to 64 bit alignment */
> } xfs_dsb_t;
>
> /*
> @@ -223,7 +244,7 @@ typedef enum {
> XFS_SBS_GQUOTINO, XFS_SBS_QFLAGS, XFS_SBS_FLAGS, XFS_SBS_SHARED_VN,
> XFS_SBS_INOALIGNMT, XFS_SBS_UNIT, XFS_SBS_WIDTH, XFS_SBS_DIRBLKLOG,
> XFS_SBS_LOGSECTLOG, XFS_SBS_LOGSECTSIZE, XFS_SBS_LOGSUNIT,
> - XFS_SBS_FEATURES2,
> + XFS_SBS_FEATURES2, XFS_SBS_BAD_FEATURES2,
> XFS_SBS_FIELDCOUNT
> } xfs_sb_field_t;
>
> @@ -248,13 +269,15 @@ typedef enum {
> #define XFS_SB_IFREE XFS_SB_MVAL(IFREE)
> #define XFS_SB_FDBLOCKS XFS_SB_MVAL(FDBLOCKS)
> #define XFS_SB_FEATURES2 XFS_SB_MVAL(FEATURES2)
> +#define XFS_SB_BAD_FEATURES2 XFS_SB_MVAL(BAD_FEATURES2)
> #define XFS_SB_NUM_BITS ((int)XFS_SBS_FIELDCOUNT)
> #define XFS_SB_ALL_BITS ((1LL << XFS_SB_NUM_BITS) - 1)
> #define XFS_SB_MOD_BITS \
> (XFS_SB_UUID | XFS_SB_ROOTINO | XFS_SB_RBMINO | XFS_SB_RSUMINO | \
> XFS_SB_VERSIONNUM | XFS_SB_UQUOTINO | XFS_SB_GQUOTINO | \
> XFS_SB_QFLAGS | XFS_SB_SHARED_VN | XFS_SB_UNIT | XFS_SB_WIDTH | \
> - XFS_SB_ICOUNT | XFS_SB_IFREE | XFS_SB_FDBLOCKS | XFS_SB_FEATURES2)
> + XFS_SB_ICOUNT | XFS_SB_IFREE | XFS_SB_FDBLOCKS | XFS_SB_FEATURES2 | \
> + XFS_SB_BAD_FEATURES2)
>
>
> /*
> @@ -297,6 +320,14 @@ static inline int xfs_sb_good_version(xf
> }
> #endif /* __KERNEL__ */
>
> +/*
> + * Detect a bad features2 field
> + */
> +static inline int xfs_sb_has_bad_features2(xfs_sb_t *sbp)
> +{
> + return (sbp->sb_bad_features2 != 0);
> +}
> +
> #define XFS_SB_VERSION_TONEW(v) xfs_sb_version_tonew(v)
> static inline unsigned xfs_sb_version_tonew(unsigned v)
> {
>
>
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