Re: [PATCH 18/22] xfs: scrub extended attributes

Allison Henderson
2017-07-23T17:57:43Z

Reviewed by: Allison Henderson <allison.henderson@oracle.com>

On 7/20/2017 9:40 PM, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
>
> Scrub the hash tree, keys, and values in an extended attribute structure.
> Refactor the attribute code to use the transaction if the caller supplied
> one to avoid buffer deadocks.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
> fs/xfs/Makefile | 1
> fs/xfs/libxfs/xfs_fs.h | 3 -
> fs/xfs/scrub/attr.c | 212 ++++++++++++++++++++++++++++++++++++++++++++++++
> fs/xfs/scrub/common.c | 8 ++
> fs/xfs/scrub/common.h | 3 +
> fs/xfs/xfs_trace.h | 3 -
> 6 files changed, 228 insertions(+), 2 deletions(-)
> create mode 100644 fs/xfs/scrub/attr.c
>
>
> diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
> index c568d0d..da64bef 100644
> --- a/fs/xfs/Makefile
> +++ b/fs/xfs/Makefile
> @@ -142,6 +142,7 @@ ifeq ($(CONFIG_XFS_ONLINE_SCRUB),y)
> xfs-y += $(addprefix scrub/, \
> agheader.o \
> alloc.o \
> + attr.o \
> bmap.o \
> btree.o \
> common.o \
> diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
> index e646b5f..2f553ed 100644
> --- a/fs/xfs/libxfs/xfs_fs.h
> +++ b/fs/xfs/libxfs/xfs_fs.h
> @@ -498,7 +498,8 @@ struct xfs_scrub_metadata {
> #define XFS_SCRUB_TYPE_BMBTA 14 /* attr fork block mapping */
> #define XFS_SCRUB_TYPE_BMBTC 15 /* CoW fork block mapping */
> #define XFS_SCRUB_TYPE_DIR 16 /* directory */
> -#define XFS_SCRUB_TYPE_MAX 16
> +#define XFS_SCRUB_TYPE_XATTR 17 /* extended attribute */
> +#define XFS_SCRUB_TYPE_MAX 17
>
> /* i: repair this metadata */
> #define XFS_SCRUB_FLAG_REPAIR (1 << 0)
> diff --git a/fs/xfs/scrub/attr.c b/fs/xfs/scrub/attr.c
> new file mode 100644
> index 0000000..f6a4b59
> --- /dev/null
> +++ b/fs/xfs/scrub/attr.c
> @@ -0,0 +1,212 @@
> +/*
> + * Copyright (C) 2017 Oracle. All Rights Reserved.
> + *
> + * Author: Darrick J. Wong <darrick.wong@oracle.com>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version 2
> + * of the License, or (at your option) any later version.
> + *
> + * This program is distributed in the hope that it would be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write the Free Software Foundation,
> + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
> + */
> +#include "xfs.h"
> +#include "xfs_fs.h"
> +#include "xfs_shared.h"
> +#include "xfs_format.h"
> +#include "xfs_trans_resv.h"
> +#include "xfs_mount.h"
> +#include "xfs_defer.h"
> +#include "xfs_btree.h"
> +#include "xfs_bit.h"
> +#include "xfs_log_format.h"
> +#include "xfs_trans.h"
> +#include "xfs_trace.h"
> +#include "xfs_sb.h"
> +#include "xfs_inode.h"
> +#include "xfs_da_format.h"
> +#include "xfs_da_btree.h"
> +#include "xfs_dir2.h"
> +#include "xfs_attr.h"
> +#include "xfs_attr_leaf.h"
> +#include "scrub/common.h"
> +#include "scrub/dabtree.h"
> +
> +#include <linux/posix_acl_xattr.h>
> +#include <linux/xattr.h>
> +
> +/* Set us up to scrub an inode's extended attributes. */
> +int
> +xfs_scrub_setup_xattr(
> + struct xfs_scrub_context *sc,
> + struct xfs_inode *ip)
> +{
> + /* Allocate the buffer without the inode lock held. */
> + sc->buf = kmem_zalloc_large(XATTR_SIZE_MAX, KM_SLEEP);
> + if (!sc->buf)
> + return -ENOMEM;
> +
> + return xfs_scrub_setup_inode_contents(sc, ip, 0);
> +}
> +
> +/* Extended Attributes */
> +
> +struct xfs_scrub_xattr {
> + struct xfs_attr_list_context context;
> + struct xfs_scrub_context *sc;
> +};
> +
> +#define XFS_SCRUB_ATTR_CHECK(fs_ok) \
> + XFS_SCRUB_DATA_CHECK(sx->sc, XFS_ATTR_FORK, args.blkno, "attr", fs_ok)
> +#define XFS_SCRUB_ATTR_OP_ERROR_GOTO(label) \
> + XFS_SCRUB_FILE_OP_ERROR_GOTO(sx->sc, XFS_ATTR_FORK, args.blkno, "attr", &error, label)
> +/* Check that an extended attribute key can be looked up by hash. */
> +static void
> +xfs_scrub_xattr_listent(
> + struct xfs_attr_list_context *context,
> + int flags,
> + unsigned char *name,
> + int namelen,
> + int valuelen)
> +{
> + struct xfs_scrub_xattr *sx;
> + struct xfs_da_args args = {0};
> + int error = 0;
> +
> + sx = container_of(context, struct xfs_scrub_xattr, context);
> +
> + args.flags = ATTR_KERNOTIME;
> + if (flags & XFS_ATTR_ROOT)
> + args.flags |= ATTR_ROOT;
> + else if (flags & XFS_ATTR_SECURE)
> + args.flags |= ATTR_SECURE;
> + args.geo = context->dp->i_mount->m_attr_geo;
> + args.whichfork = XFS_ATTR_FORK;
> + args.dp = context->dp;
> + args.name = name;
> + args.namelen = namelen;
> + args.hashval = xfs_da_hashname(args.name, args.namelen);
> + args.trans = context->tp;
> + args.value = sx->sc->buf;
> + args.valuelen = XATTR_SIZE_MAX;
> +
> + error = xfs_attr_get_ilocked(context->dp, &args);
> + if (error == -EEXIST)
> + error = 0;
> + XFS_SCRUB_ATTR_OP_ERROR_GOTO(fail_xref);
> + XFS_SCRUB_ATTR_CHECK(args.valuelen == valuelen);
> +
> +fail_xref:
> + return;
> +}
> +#undef XFS_SCRUB_ATTR_OP_ERROR_GOTO
> +#undef XFS_SCRUB_ATTR_CHECK
> +
> +/* Scrub a attribute btree record. */
> +STATIC int
> +xfs_scrub_xattr_rec(
> + struct xfs_scrub_da_btree *ds,
> + int level,
> + void *rec)
> +{
> + struct xfs_mount *mp = ds->state->mp;
> + struct xfs_attr_leaf_entry *ent = rec;
> + struct xfs_da_state_blk *blk;
> + struct xfs_attr_leaf_name_local *lentry;
> + struct xfs_attr_leaf_name_remote *rentry;
> + struct xfs_buf *bp;
> + xfs_dahash_t calc_hash;
> + xfs_dahash_t hash;
> + int nameidx;
> + int hdrsize;
> + unsigned int badflags;
> + int error;
> +
> + blk = &ds->state->path.blk[level];
> +
> + /* Check the hash of the entry. */
> + error = xfs_scrub_da_btree_hash(ds, level, &ent->hashval);
> + if (error)
> + goto out;
> +
> + /* Find the attr entry's location. */
> + bp = blk->bp;
> + hdrsize = xfs_attr3_leaf_hdr_size(bp->b_addr);
> + nameidx = be16_to_cpu(ent->nameidx);
> + XFS_SCRUB_DA_GOTO(ds, nameidx >= hdrsize, out);
> + XFS_SCRUB_DA_GOTO(ds, nameidx < mp->m_attr_geo->blksize, out);
> +
> + /* Retrieve the entry and check it. */
> + hash = be32_to_cpu(ent->hashval);
> + badflags = ~(XFS_ATTR_LOCAL | XFS_ATTR_ROOT | XFS_ATTR_SECURE |
> + XFS_ATTR_INCOMPLETE);
> + XFS_SCRUB_DA_CHECK(ds, (ent->flags & badflags) == 0);
> + if (ent->flags & XFS_ATTR_LOCAL) {
> + lentry = (struct xfs_attr_leaf_name_local *)
> + (((char *)bp->b_addr) + nameidx);
> + XFS_SCRUB_DA_GOTO(ds, lentry->namelen < MAXNAMELEN, out);
> + calc_hash = xfs_da_hashname(lentry->nameval, lentry->namelen);
> + } else {
> + rentry = (struct xfs_attr_leaf_name_remote *)
> + (((char *)bp->b_addr) + nameidx);
> + XFS_SCRUB_DA_GOTO(ds, rentry->namelen < MAXNAMELEN, out);
> + calc_hash = xfs_da_hashname(rentry->name, rentry->namelen);
> + }
> + XFS_SCRUB_DA_CHECK(ds, calc_hash == hash);
> +
> +out:
> + return error;
> +}
> +
> +/* Scrub the extended attribute metadata. */
> +int
> +xfs_scrub_xattr(
> + struct xfs_scrub_context *sc)
> +{
> + struct xfs_scrub_xattr sx = { 0 };
> + struct attrlist_cursor_kern cursor = { 0 };
> + struct xfs_mount *mp = sc->mp;
> + int error = 0;
> +
> + if (!xfs_inode_hasattr(sc->ip))
> + return -ENOENT;
> +
> + memset(&sx, 0, sizeof(sx));
> + /* Check attribute tree structure */
> + error = xfs_scrub_da_btree(sc, XFS_ATTR_FORK, xfs_scrub_xattr_rec);
> + if (error)
> + goto out;
> +
> + /* Check that every attr key can also be looked up by hash. */
> + sx.context.dp = sc->ip;
> + sx.context.cursor = &cursor;
> + sx.context.resynch = 1;
> + sx.context.put_listent = xfs_scrub_xattr_listent;
> + sx.context.tp = sc->tp;
> + sx.sc = sc;
> +
> + /*
> + * Look up every xattr in this file by name.
> + *
> + * The VFS only locks i_rwsem when modifying attrs, so keep all
> + * three locks held because that's the only way to ensure we're
> + * the only thread poking into the da btree. We traverse the da
> + * btree while holding a leaf buffer locked for the xattr name
> + * iteration, which doesn't really follow the usual buffer
> + * locking order.
> + */
> + error = xfs_attr_list_int_ilocked(&sx.context);
> + XFS_SCRUB_OP_ERROR_GOTO(sc,
> + XFS_INO_TO_AGNO(mp, sc->ip->i_ino),
> + XFS_INO_TO_AGBNO(mp, sc->ip->i_ino),
> + "inode", &error, out);
> +out:
> + return error;
> +}
> diff --git a/fs/xfs/scrub/common.c b/fs/xfs/scrub/common.c
> index 92627e9..a47c654 100644
> --- a/fs/xfs/scrub/common.c
> +++ b/fs/xfs/scrub/common.c
> @@ -686,6 +686,10 @@ xfs_scrub_teardown(
> IRELE(sc->ip);
> sc->ip = NULL;
> }
> + if (sc->buf) {
> + kmem_free(sc->buf);
> + sc->buf = NULL;
> + }
> return error;
> }
>
> @@ -844,6 +848,10 @@ static const struct xfs_scrub_meta_fns meta_scrub_fns[] = {
> .setup = xfs_scrub_setup_directory,
> .scrub = xfs_scrub_directory,
> },
> + { /* extended attributes */
> + .setup = xfs_scrub_setup_xattr,
> + .scrub = xfs_scrub_xattr,
> + },
> };
>
> /* Dispatch metadata scrubbing. */
> diff --git a/fs/xfs/scrub/common.h b/fs/xfs/scrub/common.h
> index 7baaa2d..1cfe0cc 100644
> --- a/fs/xfs/scrub/common.h
> +++ b/fs/xfs/scrub/common.h
> @@ -52,6 +52,7 @@ struct xfs_scrub_context {
> const struct xfs_scrub_meta_fns *fns;
> struct xfs_trans *tp;
> struct xfs_inode *ip;
> + void *buf;
> uint ilock_flags;
> bool try_harder;
>
> @@ -221,6 +222,7 @@ SETUP_FN(xfs_scrub_setup_inode);
> SETUP_FN(xfs_scrub_setup_inode_bmap_data);
> SETUP_FN(xfs_scrub_setup_inode_bmap);
> SETUP_FN(xfs_scrub_setup_directory);
> +SETUP_FN(xfs_scrub_setup_xattr);
> #undef SETUP_FN
>
> /* Metadata scrubbers */
> @@ -243,6 +245,7 @@ SCRUB_FN(xfs_scrub_bmap_data);
> SCRUB_FN(xfs_scrub_bmap_attr);
> SCRUB_FN(xfs_scrub_bmap_cow);
> SCRUB_FN(xfs_scrub_directory);
> +SCRUB_FN(xfs_scrub_xattr);
> #undef SCRUB_FN
>
> #endif /* __XFS_REPAIR_COMMON_H__ */
> diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
> index ccd27ec..fe4b313 100644
> --- a/fs/xfs/xfs_trace.h
> +++ b/fs/xfs/xfs_trace.h
> @@ -3328,7 +3328,8 @@ DEFINE_GETFSMAP_EVENT(xfs_getfsmap_mapping);
> { XFS_SCRUB_TYPE_BMBTD, "bmapbtd" }, \
> { XFS_SCRUB_TYPE_BMBTA, "bmapbta" }, \
> { XFS_SCRUB_TYPE_BMBTC, "bmapbtc" }, \
> - { XFS_SCRUB_TYPE_DIR, "dir" }
> + { XFS_SCRUB_TYPE_DIR, "dir" }, \
> + { XFS_SCRUB_TYPE_XATTR, "xattr" }
> DECLARE_EVENT_CLASS(xfs_scrub_class,
> TP_PROTO(struct xfs_inode *ip, struct xfs_scrub_metadata *sm,
> int error),
>
> --
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