Re: [PATCH 7/7] xfs: Extend attr extent counter to 32 bits

Darrick J. Wong
2020-06-08T17:21:36Z

On Sat, Jun 06, 2020 at 01:57:45PM +0530, Chandan Babu R wrote:
> This commit extends the per-inode attr extent counter to 32 bits.
>
> The following changes are made to accomplish this,
> 1. A new ro-compat superblock flag to prevent older kernels from
> mounting the filesystem in read-write mode. This flag is set for the
> first time when an inode would end up having more than 2^15 extents.
> 3. Carve out a new 16-bit field from xfs_dinode->di_pad2[]. This field
> holds the most significant 16 bits of the attr extent counter.

How difficult is it to end up with an attr fork mapping more than 2^32
blocks? Supposing I have a file with nlinks==2^32-1, each mapped to a
255-byte name and some number of other xattrs?

> 2. A new inode->di_flags2 flag to indicate that the newly added field
> contains valid data. This flag is set when one of the following two
> conditions are met,
> - When the inode is about to have more than 2^15 extents.
> - When flushing the incore inode (See xfs_iflush_int()), if
> the superblock ro-compat flag is already set.
>
> Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
> ---
> fs/xfs/libxfs/xfs_format.h | 25 ++++++++++---
> fs/xfs/libxfs/xfs_inode_buf.c | 23 +++++++++---
> fs/xfs/libxfs/xfs_inode_fork.c | 62 ++++++++++++++++++++++++++-------
> fs/xfs/libxfs/xfs_log_format.h | 5 +--
> fs/xfs/libxfs/xfs_types.h | 5 +--
> fs/xfs/scrub/inode.c | 5 +--
> fs/xfs/xfs_inode.c | 4 +++
> fs/xfs/xfs_inode_item.c | 5 ++-
> fs/xfs/xfs_inode_item_recover.c | 8 ++++-
> 9 files changed, 113 insertions(+), 29 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
> index 91bee33aa988..2e37d887fd35 100644
> --- a/fs/xfs/libxfs/xfs_format.h
> +++ b/fs/xfs/libxfs/xfs_format.h
> @@ -450,11 +450,13 @@ xfs_sb_has_compat_feature(
> #define XFS_SB_FEAT_RO_COMPAT_RMAPBT (1 << 1) /* reverse map btree */
> #define XFS_SB_FEAT_RO_COMPAT_REFLINK (1 << 2) /* reflinked files */
> #define XFS_SB_FEAT_RO_COMPAT_47BIT_DEXT_CNTR (1 << 3) /* 47bit data extents */
> +#define XFS_SB_FEAT_RO_COMPAT_32BIT_AEXT_CNTR (1 << 4) /* 32bit attr extents */

Can we bundle both of these changes in a single feature flag? I would
like to keep our feature testing matrix as small as we can.

/* 64-bit data fork extent counts and 32-bit attr fork extent counts */
#define XFS_SB_FEAT_RO_COMPAT_BIG_FORK (1 << 4)

> #define XFS_SB_FEAT_RO_COMPAT_ALL \
> (XFS_SB_FEAT_RO_COMPAT_FINOBT | \
> XFS_SB_FEAT_RO_COMPAT_RMAPBT | \
> XFS_SB_FEAT_RO_COMPAT_REFLINK | \
> - XFS_SB_FEAT_RO_COMPAT_47BIT_DEXT_CNTR)
> + XFS_SB_FEAT_RO_COMPAT_47BIT_DEXT_CNTR | \
> + XFS_SB_FEAT_RO_COMPAT_32BIT_AEXT_CNTR)
> #define XFS_SB_FEAT_RO_COMPAT_UNKNOWN ~XFS_SB_FEAT_RO_COMPAT_ALL
> static inline bool
> xfs_sb_has_ro_compat_feature(
> @@ -577,6 +579,18 @@ static inline void xfs_sb_version_add47bitext(struct xfs_sb *sbp)
> sbp->sb_features_ro_compat |= XFS_SB_FEAT_RO_COMPAT_47BIT_DEXT_CNTR;
> }
>
> +static inline bool xfs_sb_version_has32bitaext(struct xfs_sb *sbp)
> +{
> + return XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5 &&
> + (sbp->sb_features_ro_compat &
> + XFS_SB_FEAT_RO_COMPAT_32BIT_AEXT_CNTR);
> +}
> +
> +static inline void xfs_sb_version_add32bitaext(struct xfs_sb *sbp)
> +{
> + sbp->sb_features_ro_compat |= XFS_SB_FEAT_RO_COMPAT_32BIT_AEXT_CNTR;
> +}
> +
> /*
> * end of superblock version macros
> */
> @@ -888,7 +902,7 @@ typedef struct xfs_dinode {
> __be64 di_nblocks; /* # of direct & btree blocks used */
> __be32 di_extsize; /* basic/minimum extent size for file */
> __be32 di_nextents_lo; /* number of extents in data fork */
> - __be16 di_anextents; /* number of extents in attribute fork*/
> + __be16 di_anextents_lo;/* lower part of xattr extent count */
> __u8 di_forkoff; /* attr fork offs, <<3 for 64b align */
> __s8 di_aformat; /* format of attr fork's data */
> __be32 di_dmevmask; /* DMIG event mask */
> @@ -906,7 +920,8 @@ typedef struct xfs_dinode {
> __be64 di_flags2; /* more random flags */
> __be32 di_cowextsize; /* basic cow extent size for file */
> __be32 di_nextents_hi;
> - __u8 di_pad2[8]; /* more padding for future expansion */
> + __be16 di_anextents_hi;/* higher part of xattr extent count */
> + __u8 di_pad2[6]; /* more padding for future expansion */
>
> /* fields only written to during inode creation */
> xfs_timestamp_t di_crtime; /* time created */
> @@ -1073,14 +1088,16 @@ static inline void xfs_dinode_put_rdev(struct xfs_dinode *dip, xfs_dev_t rdev)
> #define XFS_DIFLAG2_REFLINK_BIT 1 /* file's blocks may be shared */
> #define XFS_DIFLAG2_COWEXTSIZE_BIT 2 /* copy on write extent size hint */
> #define XFS_DIFLAG2_47BIT_NEXTENTS_BIT 3 /* Uses di_nextents_hi field */
> +#define XFS_DIFLAG2_32BIT_ANEXTENTS_BIT 4 /* Uses di_anextents_hi field */

Same thing here.

> #define XFS_DIFLAG2_DAX (1 << XFS_DIFLAG2_DAX_BIT)
> #define XFS_DIFLAG2_REFLINK (1 << XFS_DIFLAG2_REFLINK_BIT)
> #define XFS_DIFLAG2_COWEXTSIZE (1 << XFS_DIFLAG2_COWEXTSIZE_BIT)
> #define XFS_DIFLAG2_47BIT_NEXTENTS (1 << XFS_DIFLAG2_47BIT_NEXTENTS_BIT)
> +#define XFS_DIFLAG2_32BIT_ANEXTENTS (1 << XFS_DIFLAG2_32BIT_ANEXTENTS_BIT)
>
> #define XFS_DIFLAG2_ANY \
> (XFS_DIFLAG2_DAX | XFS_DIFLAG2_REFLINK | XFS_DIFLAG2_COWEXTSIZE | \
> - XFS_DIFLAG2_47BIT_NEXTENTS)
> + XFS_DIFLAG2_47BIT_NEXTENTS | XFS_DIFLAG2_32BIT_ANEXTENTS)
>
> /*
> * Inode number format:
> diff --git a/fs/xfs/libxfs/xfs_inode_buf.c b/fs/xfs/libxfs/xfs_inode_buf.c
> index 8b89fe080f70..285cbce0cd10 100644
> --- a/fs/xfs/libxfs/xfs_inode_buf.c
> +++ b/fs/xfs/libxfs/xfs_inode_buf.c
> @@ -309,7 +309,8 @@ xfs_inode_to_disk(
> to->di_extsize = cpu_to_be32(from->di_extsize);
> to->di_nextents_lo = cpu_to_be32(xfs_ifork_nextents(&ip->i_df) &
> 0xffffffffU);
> - to->di_anextents = cpu_to_be16(xfs_ifork_nextents(ip->i_afp));
> + to->di_anextents_lo = cpu_to_be16(xfs_ifork_nextents(ip->i_afp) &
> + 0xffffU);
> to->di_forkoff = from->di_forkoff;
> to->di_aformat = xfs_ifork_format(ip->i_afp);
> to->di_dmevmask = cpu_to_be32(from->di_dmevmask);
> @@ -327,6 +328,10 @@ xfs_inode_to_disk(
> to->di_nextents_hi
> = cpu_to_be32(xfs_ifork_nextents(&ip->i_df)
> >> 32);
> + if (from->di_flags2 & XFS_DIFLAG2_32BIT_ANEXTENTS)
> + to->di_anextents_hi
> + = cpu_to_be16(xfs_ifork_nextents(ip->i_afp)
> + >> 16);
> to->di_ino = cpu_to_be64(ip->i_ino);
> to->di_lsn = cpu_to_be64(lsn);
> memset(to->di_pad2, 0, sizeof(to->di_pad2));
> @@ -366,7 +371,7 @@ xfs_log_dinode_to_disk(
> to->di_nblocks = cpu_to_be64(from->di_nblocks);
> to->di_extsize = cpu_to_be32(from->di_extsize);
> to->di_nextents_lo = cpu_to_be32(from->di_nextents_lo);
> - to->di_anextents = cpu_to_be16(from->di_anextents);
> + to->di_anextents_lo = cpu_to_be16(from->di_anextents_lo);
> to->di_forkoff = from->di_forkoff;
> to->di_aformat = from->di_aformat;
> to->di_dmevmask = cpu_to_be32(from->di_dmevmask);
> @@ -383,6 +388,9 @@ xfs_log_dinode_to_disk(
> if (from->di_flags2 & XFS_DIFLAG2_47BIT_NEXTENTS)
> to->di_nextents_hi =
> cpu_to_be32(from->di_nextents_hi);
> + if (from->di_flags2 & XFS_DIFLAG2_32BIT_ANEXTENTS)
> + to->di_anextents_hi =
> + cpu_to_be16(from->di_anextents_hi);
> to->di_ino = cpu_to_be64(from->di_ino);
> to->di_lsn = cpu_to_be64(from->di_lsn);
> memcpy(to->di_pad2, from->di_pad2, sizeof(to->di_pad2));
> @@ -566,7 +574,7 @@ xfs_dinode_verify(
> default:
> return __this_address;
> }
> - if (dip->di_anextents)
> + if (xfs_dfork_nextents(&mp->m_sb, dip, XFS_ATTR_FORK))
> return __this_address;
> }
>
> @@ -745,8 +753,13 @@ xfs_dfork_nextents(
> && (dip->di_flags2 & XFS_DIFLAG2_47BIT_NEXTENTS))
> nextents |= (u64)(be32_to_cpu(dip->di_nextents_hi))
> << 32;
> - return nextents;
> } else {
> - return be16_to_cpu(dip->di_anextents);
> + nextents = be16_to_cpu(dip->di_anextents_lo);
> + if (xfs_sb_version_has_v3inode(sbp)
> + && (dip->di_flags2 & XFS_DIFLAG2_32BIT_ANEXTENTS))
> + nextents |= (u32)(be16_to_cpu(dip->di_anextents_hi))

<same if test logic vs. if body statement indentation complaint>

> + << 16;
> }
> +
> + return nextents;
> }
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
> index ec682e2d5bcb..169e16947ece 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.c
> +++ b/fs/xfs/libxfs/xfs_inode_fork.c
> @@ -301,7 +301,10 @@ xfs_iformat_attr_fork(
> ip->i_afp->if_format = dip->di_aformat;
> if (unlikely(ip->i_afp->if_format == 0)) /* pre IRIX 6.2 file system */
> ip->i_afp->if_format = XFS_DINODE_FMT_EXTENTS;
> - ip->i_afp->if_nextents = be16_to_cpu(dip->di_anextents);
> + ip->i_afp->if_nextents = be16_to_cpu(dip->di_anextents_lo);
> + if (ip->i_d.di_flags2 & XFS_DIFLAG2_32BIT_ANEXTENTS)
> + ip->i_afp->if_nextents |=
> + (u32)(be16_to_cpu(dip->di_anextents_hi)) << 16;
>
> switch (ip->i_afp->if_format) {
> case XFS_DINODE_FMT_LOCAL:
> @@ -777,6 +780,48 @@ xfs_next_set_data(
> return 0;
> }
>
> +static int
> +xfs_next_set_attr(
> + struct xfs_trans *tp,
> + struct xfs_inode *ip,
> + struct xfs_ifork *ifp,
> + int delta)
> +{
> + struct xfs_mount *mp = ip->i_mount;
> + xfs_aextnum_t nr_exts;
> +
> + nr_exts = ifp->if_nextents + delta;
> +
> + if ((delta > 0 && nr_exts < ifp->if_nextents) ||
> + (delta < 0 && nr_exts > ifp->if_nextents))
> + return -EOVERFLOW;
> +
> + if (ifp->if_nextents <= MAXAEXTNUM15BIT &&
> + nr_exts > MAXAEXTNUM15BIT &&
> + !(ip->i_d.di_flags2 & XFS_DIFLAG2_32BIT_ANEXTENTS) &&
> + xfs_sb_version_has_v3inode(&mp->m_sb)) {
> + if (!xfs_sb_version_has32bitaext(&mp->m_sb)) {

Indentation complaint^2

> + bool log_sb = false;
> +
> + spin_lock(&mp->m_sb_lock);
> + if (!xfs_sb_version_has32bitaext(&mp->m_sb)) {
> + xfs_sb_version_add32bitaext(&mp->m_sb);
> + log_sb = true;
> + }
> + spin_unlock(&mp->m_sb_lock);
> +
> + if (log_sb)
> + xfs_log_sb(tp);
> + }
> +
> + ip->i_d.di_flags2 |= XFS_DIFLAG2_32BIT_ANEXTENTS;
> + }
> +
> + ifp->if_nextents = nr_exts;
> +
> + return 0;
> +}
> +
> int
> xfs_next_set(
> struct xfs_trans *tp,
> @@ -785,23 +830,16 @@ xfs_next_set(
> int delta)
> {
> struct xfs_ifork *ifp;
> - int64_t nr_exts;
> int error = 0;
>
> ifp = XFS_IFORK_PTR(ip, whichfork);
>
> - if (whichfork == XFS_DATA_FORK || whichfork == XFS_COW_FORK) {
> + if (whichfork == XFS_DATA_FORK || whichfork == XFS_COW_FORK)
> error = xfs_next_set_data(tp, ip, ifp, delta);
> - } else if (whichfork == XFS_ATTR_FORK) {
> - nr_exts = ifp->if_nextents + delta;
> - if ((delta > 0 && nr_exts > MAXAEXTNUM)
> - || (delta < 0 && nr_exts < 0))
> - return -EOVERFLOW;
> -
> - ifp->if_nextents = nr_exts;
> - } else {
> + else if (whichfork == XFS_ATTR_FORK)
> + error = xfs_next_set_attr(tp, ip, ifp, delta);
> + else
> ASSERT(0);
> - }
>
> return error;
> }
> diff --git a/fs/xfs/libxfs/xfs_log_format.h b/fs/xfs/libxfs/xfs_log_format.h
> index 879aadff7692..db419fc862bc 100644
> --- a/fs/xfs/libxfs/xfs_log_format.h
> +++ b/fs/xfs/libxfs/xfs_log_format.h
> @@ -397,7 +397,7 @@ struct xfs_log_dinode {
> xfs_rfsblock_t di_nblocks; /* # of direct & btree blocks used */
> xfs_extlen_t di_extsize; /* basic/minimum extent size for file */
> uint32_t di_nextents_lo; /* number of extents in data fork */
> - xfs_aextnum_t di_anextents; /* number of extents in attribute fork*/
> + uint16_t di_anextents_lo;/* lower part of xattr extent count */
> uint8_t di_forkoff; /* attr fork offs, <<3 for 64b align */
> int8_t di_aformat; /* format of attr fork's data */
> uint32_t di_dmevmask; /* DMIG event mask */
> @@ -415,7 +415,8 @@ struct xfs_log_dinode {
> uint64_t di_flags2; /* more random flags */
> uint32_t di_cowextsize; /* basic cow extent size for file */
> uint32_t di_nextents_hi;
> - uint8_t di_pad2[8]; /* more padding for future expansion */
> + uint16_t di_anextents_hi;/* higher part of xattr extent count */
> + uint8_t di_pad2[6]; /* more padding for future expansion */
>
> /* fields only written to during inode creation */
> xfs_ictimestamp_t di_crtime; /* time created */
> diff --git a/fs/xfs/libxfs/xfs_types.h b/fs/xfs/libxfs/xfs_types.h
> index c68ff2178976..974737a9e9c1 100644
> --- a/fs/xfs/libxfs/xfs_types.h
> +++ b/fs/xfs/libxfs/xfs_types.h
> @@ -13,7 +13,7 @@ typedef uint32_t xfs_agino_t; /* inode # within allocation grp */
> typedef uint32_t xfs_extlen_t; /* extent length in blocks */
> typedef uint32_t xfs_agnumber_t; /* allocation group number */
> typedef uint64_t xfs_extnum_t; /* # of extents in a file */
> -typedef int16_t xfs_aextnum_t; /* # extents in an attribute fork */
> +typedef uint32_t xfs_aextnum_t; /* # extents in an attribute fork */
> typedef int64_t xfs_fsize_t; /* bytes in a file */
> typedef uint64_t xfs_ufsize_t; /* unsigned bytes in a file */
>
> @@ -62,7 +62,8 @@ typedef void * xfs_failaddr_t;
> #define MAXEXTNUM31BIT ((xfs_extnum_t)0x7fffffff) /* 31 bits */
> #define MAXEXTNUM ((xfs_extnum_t)0x7fffffffffff) /* 47 bits */
> #define MAXDIREXTNUM ((xfs_extnum_t)0x7ffffff) /* 27 bits */
> -#define MAXAEXTNUM ((xfs_aextnum_t)0x7fff) /* signed short */
> +#define MAXAEXTNUM15BIT ((xfs_aextnum_t)0x7fff) /* 15 bits */
> +#define MAXAEXTNUM ((xfs_aextnum_t)0xffffffff) /* 32 bits */
>
> /*
> * Minimum and maximum blocksize and sectorsize.
> diff --git a/fs/xfs/scrub/inode.c b/fs/xfs/scrub/inode.c
> index be41fd242ff2..01e60c78a3a3 100644
> --- a/fs/xfs/scrub/inode.c
> +++ b/fs/xfs/scrub/inode.c
> @@ -371,10 +371,12 @@ xchk_dinode(
> break;
> }
>
> + nextents = xfs_dfork_nextents(&mp->m_sb, dip, XFS_ATTR_FORK);
> +
> /* di_forkoff */
> if (XFS_DFORK_APTR(dip) >= (char *)dip + mp->m_sb.sb_inodesize)
> xchk_ino_set_corrupt(sc, ino);
> - if (dip->di_anextents != 0 && dip->di_forkoff == 0)
> + if (nextents != 0 && dip->di_forkoff == 0)
> xchk_ino_set_corrupt(sc, ino);
> if (dip->di_forkoff == 0 && dip->di_aformat != XFS_DINODE_FMT_EXTENTS)
> xchk_ino_set_corrupt(sc, ino);
> @@ -386,7 +388,6 @@ xchk_dinode(
> xchk_ino_set_corrupt(sc, ino);
>
> /* di_anextents */
> - nextents = be16_to_cpu(dip->di_anextents);
> fork_recs = XFS_DFORK_ASIZE(dip, mp) / sizeof(struct xfs_bmbt_rec);
> switch (dip->di_aformat) {
> case XFS_DINODE_FMT_EXTENTS:
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index 4418a66cf6d6..6ec34e069344 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -3789,6 +3789,10 @@ xfs_iflush_int(
> && xfs_sb_version_has47bitext(&mp->m_sb))
> ip->i_d.di_flags2 |= XFS_DIFLAG2_47BIT_NEXTENTS;
>
> + if (!(ip->i_d.di_flags2 & XFS_DIFLAG2_32BIT_ANEXTENTS)
> + && xfs_sb_version_has32bitaext(&mp->m_sb))
> + ip->i_d.di_flags2 |= XFS_DIFLAG2_32BIT_ANEXTENTS;
> +
> /*
> * Copy the dirty parts of the inode into the on-disk inode. We always
> * copy out the core of the inode, because if the inode is dirty at all
> diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c
> index 6f27ac7c8631..40f0a19d1c07 100644
> --- a/fs/xfs/xfs_inode_item.c
> +++ b/fs/xfs/xfs_inode_item.c
> @@ -327,7 +327,7 @@ xfs_inode_to_log_dinode(
> to->di_nblocks = from->di_nblocks;
> to->di_extsize = from->di_extsize;
> to->di_nextents_lo = xfs_ifork_nextents(&ip->i_df) & 0xffffffffU;
> - to->di_anextents = xfs_ifork_nextents(ip->i_afp);
> + to->di_anextents_lo = xfs_ifork_nextents(ip->i_afp) & 0xffffU;
> to->di_forkoff = from->di_forkoff;
> to->di_aformat = xfs_ifork_format(ip->i_afp);
> to->di_dmevmask = from->di_dmevmask;
> @@ -347,6 +347,9 @@ xfs_inode_to_log_dinode(
> if (from->di_flags2 & XFS_DIFLAG2_47BIT_NEXTENTS)
> to->di_nextents_hi =
> xfs_ifork_nextents(&ip->i_df) >> 32;
> + if (from->di_flags2 & XFS_DIFLAG2_32BIT_ANEXTENTS)
> + to->di_anextents_hi =
> + xfs_ifork_nextents(ip->i_afp) >> 16;
> to->di_ino = ip->i_ino;
> to->di_lsn = lsn;
> memset(to->di_pad2, 0, sizeof(to->di_pad2));
> diff --git a/fs/xfs/xfs_inode_item_recover.c b/fs/xfs/xfs_inode_item_recover.c
> index 8d64b861fb66..c8b5fbba848b 100644
> --- a/fs/xfs/xfs_inode_item_recover.c
> +++ b/fs/xfs/xfs_inode_item_recover.c
> @@ -135,6 +135,7 @@ xlog_recover_inode_commit_pass2(
> uint isize;
> int need_free = 0;
> xfs_extnum_t nextents;
> + xfs_aextnum_t anextents;
>
> if (item->ri_buf[0].i_len == sizeof(struct xfs_inode_log_format)) {
> in_f = item->ri_buf[0].i_addr;
> @@ -262,7 +263,12 @@ xlog_recover_inode_commit_pass2(
> ldip->di_flags2 & XFS_DIFLAG2_47BIT_NEXTENTS)
> nextents |= ((u64)(ldip->di_nextents_hi) << 32);
>
> - nextents += ldip->di_anextents;
> + anextents = ldip->di_anextents_lo;
> + if (xfs_sb_version_has_v3inode(&mp->m_sb) &&
> + ldip->di_flags2 & XFS_DIFLAG2_32BIT_ANEXTENTS)
> + anextents |= ((u32)(ldip->di_anextents_hi) << 16);
> +
> + nextents += anextents;
>
> if (unlikely(nextents > ldip->di_nblocks)) {
> XFS_CORRUPTION_ERROR("xlog_recover_inode_pass2(5)",
> --
> 2.20.1
>