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[PATCH 2/7] factor out xfs_read_agf helper

To: xfs@xxxxxxxxxxx
Subject: [PATCH 2/7] factor out xfs_read_agf helper
From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Mon, 27 Oct 2008 09:39:03 -0400
User-agent: quilt/0.46-1
Add a helper to read the AGF header and perform basic verification.
Based on hunks from a larger patch from Dave Chinner.

(First sent on Juli 23rd)


Signed-off-by: Christoph Hellwig <hch@xxxxxx>

Index: linux-2.6-xfs/fs/xfs/xfs_ag.h
===================================================================
--- linux-2.6-xfs.orig/fs/xfs/xfs_ag.h  2008-10-01 13:46:50.000000000 +0200
+++ linux-2.6-xfs/fs/xfs/xfs_ag.h       2008-10-01 13:48:23.000000000 +0200
@@ -91,6 +91,8 @@ typedef struct xfs_agf {
 #define        XFS_AGF_BLOCK(mp)       XFS_HDR_BLOCK(mp, XFS_AGF_DADDR(mp))
 #define        XFS_BUF_TO_AGF(bp)      ((xfs_agf_t *)XFS_BUF_PTR(bp))
 
+extern int xfs_read_agf(struct xfs_mount *mp, struct xfs_trans *tp,
+                       xfs_agnumber_t agno, int flags, struct xfs_buf **bpp);
 
 /*
  * Size of the unlinked inode hash table in the agi.
Index: linux-2.6-xfs/fs/xfs/xfs_alloc.c
===================================================================
--- linux-2.6-xfs.orig/fs/xfs/xfs_alloc.c       2008-10-01 13:47:56.000000000 
+0200
+++ linux-2.6-xfs/fs/xfs/xfs_alloc.c    2008-10-01 13:49:12.000000000 +0200
@@ -2233,44 +2233,41 @@ xfs_alloc_put_freelist(
  * Read in the allocation group header (free/alloc section).
  */
 int                                    /* error */
-xfs_alloc_read_agf(
-       xfs_mount_t     *mp,            /* mount point structure */
-       xfs_trans_t     *tp,            /* transaction pointer */
-       xfs_agnumber_t  agno,           /* allocation group number */
-       int             flags,          /* XFS_ALLOC_FLAG_... */
-       xfs_buf_t       **bpp)          /* buffer for the ag freelist header */
+xfs_read_agf(
+       struct xfs_mount        *mp,    /* mount point structure */
+       struct xfs_trans        *tp,    /* transaction pointer */
+       xfs_agnumber_t          agno,   /* allocation group number */
+       int                     flags,  /* XFS_BUF_ */
+       struct xfs_buf          **bpp)  /* buffer for the ag freelist header */
 {
-       xfs_agf_t       *agf;           /* ag freelist header */
+       struct xfs_agf  *agf;           /* ag freelist header */
        int             agf_ok;         /* set if agf is consistent */
-       xfs_buf_t       *bp;            /* return value */
-       xfs_perag_t     *pag;           /* per allocation group data */
        int             error;
 
        ASSERT(agno != NULLAGNUMBER);
        error = xfs_trans_read_buf(
                        mp, tp, mp->m_ddev_targp,
                        XFS_AG_DADDR(mp, agno, XFS_AGF_DADDR(mp)),
-                       XFS_FSS_TO_BB(mp, 1),
-                       (flags & XFS_ALLOC_FLAG_TRYLOCK) ? XFS_BUF_TRYLOCK : 0U,
-                       &bp);
+                       XFS_FSS_TO_BB(mp, 1), flags, bpp);
        if (error)
                return error;
-       ASSERT(!bp || !XFS_BUF_GETERROR(bp));
-       if (!bp) {
-               *bpp = NULL;
+       if (!*bpp)
                return 0;
-       }
+
+       ASSERT(!XFS_BUF_GETERROR(*bpp));
+       agf = XFS_BUF_TO_AGF(*bpp);
+
        /*
         * Validate the magic number of the agf block.
         */
-       agf = XFS_BUF_TO_AGF(bp);
        agf_ok =
                be32_to_cpu(agf->agf_magicnum) == XFS_AGF_MAGIC &&
                XFS_AGF_GOOD_VERSION(be32_to_cpu(agf->agf_versionnum)) &&
                be32_to_cpu(agf->agf_freeblks) <= be32_to_cpu(agf->agf_length) 
&&
                be32_to_cpu(agf->agf_flfirst) < XFS_AGFL_SIZE(mp) &&
                be32_to_cpu(agf->agf_fllast) < XFS_AGFL_SIZE(mp) &&
-               be32_to_cpu(agf->agf_flcount) <= XFS_AGFL_SIZE(mp);
+               be32_to_cpu(agf->agf_flcount) <= XFS_AGFL_SIZE(mp) &&
+               be32_to_cpu(agf->agf_seqno) == agno;
        if (xfs_sb_version_haslazysbcount(&mp->m_sb))
                agf_ok = agf_ok && be32_to_cpu(agf->agf_btreeblks) <=
                                                be32_to_cpu(agf->agf_length);
@@ -2278,9 +2275,41 @@ xfs_alloc_read_agf(
                        XFS_RANDOM_ALLOC_READ_AGF))) {
                XFS_CORRUPTION_ERROR("xfs_alloc_read_agf",
                                     XFS_ERRLEVEL_LOW, mp, agf);
-               xfs_trans_brelse(tp, bp);
+               xfs_trans_brelse(tp, *bpp);
                return XFS_ERROR(EFSCORRUPTED);
        }
+
+       XFS_BUF_SET_VTYPE_REF(*bpp, B_FS_AGF, XFS_AGF_REF);
+       return 0;
+}
+
+/*
+ * Read in the allocation group header (free/alloc section).
+ */
+int                                    /* error */
+xfs_alloc_read_agf(
+       struct xfs_mount        *mp,    /* mount point structure */
+       struct xfs_trans        *tp,    /* transaction pointer */
+       xfs_agnumber_t          agno,   /* allocation group number */
+       int                     flags,  /* XFS_ALLOC_FLAG_... */
+       struct xfs_buf          **bpp)  /* buffer for the ag freelist header */
+{
+       struct xfs_agf          *agf;           /* ag freelist header */
+       struct xfs_perag        *pag;           /* per allocation group data */
+       int                     error;
+
+       ASSERT(agno != NULLAGNUMBER);
+
+       error = xfs_read_agf(mp, tp, agno,
+                       (flags & XFS_ALLOC_FLAG_TRYLOCK) ? XFS_BUF_TRYLOCK : 0,
+                       bpp);
+       if (error)
+               return error;
+       if (!*bpp)
+               return 0;
+       ASSERT(!XFS_BUF_GETERROR(*bpp));
+
+       agf = XFS_BUF_TO_AGF(*bpp);
        pag = &mp->m_perag[agno];
        if (!pag->pagf_init) {
                pag->pagf_freeblks = be32_to_cpu(agf->agf_freeblks);
@@ -2308,8 +2337,6 @@ xfs_alloc_read_agf(
                       be32_to_cpu(agf->agf_levels[XFS_BTNUM_CNTi]));
        }
 #endif
-       XFS_BUF_SET_VTYPE_REF(bp, B_FS_AGF, XFS_AGF_REF);
-       *bpp = bp;
        return 0;
 }
 
Index: linux-2.6-xfs/fs/xfs/xfs_log_recover.c
===================================================================
--- linux-2.6-xfs.orig/fs/xfs/xfs_log_recover.c 2008-10-01 13:46:50.000000000 
+0200
+++ linux-2.6-xfs/fs/xfs/xfs_log_recover.c      2008-10-01 13:48:23.000000000 
+0200
@@ -3998,7 +3998,6 @@ xlog_recover_check_summary(
        xfs_agi_t       *agip;
        xfs_buf_t       *agfbp;
        xfs_buf_t       *agibp;
-       xfs_daddr_t     agfdaddr;
        xfs_buf_t       *sbbp;
 #ifdef XFS_LOUD_RECOVERY
        xfs_sb_t        *sbp;
@@ -4015,21 +4014,18 @@ xlog_recover_check_summary(
        itotal = 0LL;
        ifree = 0LL;
        for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
-               agfdaddr = XFS_AG_DADDR(mp, agno, XFS_AGF_DADDR(mp));
-               agfbp = xfs_buf_read(mp->m_ddev_targp, agfdaddr,
-                               XFS_FSS_TO_BB(mp, 1), 0);
-               if (XFS_BUF_ISERROR(agfbp)) {
-                       xfs_ioerror_alert("xlog_recover_check_summary(agf)",
-                                               mp, agfbp, agfdaddr);
+               error = xfs_read_agf(mp, NULL, agno, 0, &agfbp);
+               if (error) {
+                       xfs_fs_cmn_err(CE_ALERT, mp,
+                                       "xlog_recover_check_summary(agf)"
+                                       "agf read failed agno %d error %d",
+                                                       agno, error);
+               } else {
+                       agfp = XFS_BUF_TO_AGF(agfbp);
+                       freeblks += be32_to_cpu(agfp->agf_freeblks) +
+                                   be32_to_cpu(agfp->agf_flcount);
+                       xfs_buf_relse(agfbp);
                }
-               agfp = XFS_BUF_TO_AGF(agfbp);
-               ASSERT(XFS_AGF_MAGIC == be32_to_cpu(agfp->agf_magicnum));
-               ASSERT(XFS_AGF_GOOD_VERSION(be32_to_cpu(agfp->agf_versionnum)));
-               ASSERT(be32_to_cpu(agfp->agf_seqno) == agno);
-
-               freeblks += be32_to_cpu(agfp->agf_freeblks) +
-                           be32_to_cpu(agfp->agf_flcount);
-               xfs_buf_relse(agfbp);
 
                error = xfs_read_agi(mp, NULL, agno, &agibp);
                if (error) {

-- 

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