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Re: [PATCH 038/119] xfs: convert unwritten status of reverse mappings

To: david@xxxxxxxxxxxxx
Subject: Re: [PATCH 038/119] xfs: convert unwritten status of reverse mappings
From: "Darrick J. Wong" <darrick.wong@xxxxxxxxxx>
Date: Wed, 29 Jun 2016 17:15:08 -0700
Cc: linux-fsdevel@xxxxxxxxxxxxxxx, vishal.l.verma@xxxxxxxxx, xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <146612651582.12839.562287367335619574.stgit@xxxxxxxxxxxxxxxx>
References: <146612627129.12839.3827886950949809165.stgit@xxxxxxxxxxxxxxxx> <146612651582.12839.562287367335619574.stgit@xxxxxxxxxxxxxxxx>
User-agent: Mutt/1.5.24 (2015-08-30)
On Thu, Jun 16, 2016 at 06:21:55PM -0700, Darrick J. Wong wrote:
> Provide a function to convert an unwritten extent to a real one and
> vice versa.
> 
> v2: Move unwritten bit to rm_offset.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
>  fs/xfs/libxfs/xfs_rmap.c |  442 
> ++++++++++++++++++++++++++++++++++++++++++++++
>  fs/xfs/xfs_trace.h       |    6 +
>  2 files changed, 448 insertions(+)
> 
> 
> diff --git a/fs/xfs/libxfs/xfs_rmap.c b/fs/xfs/libxfs/xfs_rmap.c
> index 1043c63..53ba14e 100644
> --- a/fs/xfs/libxfs/xfs_rmap.c
> +++ b/fs/xfs/libxfs/xfs_rmap.c
> @@ -610,6 +610,448 @@ out_error:
>       return error;
>  }
>  
> +#define RMAP_LEFT_CONTIG     (1 << 0)
> +#define RMAP_RIGHT_CONTIG    (1 << 1)
> +#define RMAP_LEFT_FILLING    (1 << 2)
> +#define RMAP_RIGHT_FILLING   (1 << 3)
> +#define RMAP_LEFT_VALID              (1 << 6)
> +#define RMAP_RIGHT_VALID     (1 << 7)
> +
> +#define LEFT         r[0]
> +#define RIGHT                r[1]
> +#define PREV         r[2]
> +#define NEW          r[3]
> +
> +/*
> + * Convert an unwritten extent to a real extent or vice versa.
> + * Does not handle overlapping extents.
> + */
> +STATIC int
> +__xfs_rmap_convert(
> +     struct xfs_btree_cur    *cur,
> +     xfs_agblock_t           bno,
> +     xfs_extlen_t            len,
> +     bool                    unwritten,
> +     struct xfs_owner_info   *oinfo)
> +{
> +     struct xfs_mount        *mp = cur->bc_mp;
> +     struct xfs_rmap_irec    r[4];   /* neighbor extent entries */
> +                                     /* left is 0, right is 1, prev is 2 */
> +                                     /* new is 3 */
> +     uint64_t                owner;
> +     uint64_t                offset;
> +     uint64_t                new_endoff;
> +     unsigned int            oldext;
> +     unsigned int            newext;
> +     unsigned int            flags = 0;
> +     int                     i;
> +     int                     state = 0;
> +     int                     error;
> +
> +     xfs_owner_info_unpack(oinfo, &owner, &offset, &flags);
> +     ASSERT(!(XFS_RMAP_NON_INODE_OWNER(owner) ||
> +                     (flags & (XFS_RMAP_ATTR_FORK | XFS_RMAP_BMBT_BLOCK))));
> +     oldext = unwritten ? XFS_RMAP_UNWRITTEN : 0;
> +     new_endoff = offset + len;
> +     trace_xfs_rmap_convert(mp, cur->bc_private.a.agno, bno, len,
> +                     unwritten, oinfo);
> +
> +     /*
> +      * For the initial lookup, look for and exact match or the left-adjacent
> +      * record for our insertion point. This will also give us the record for
> +      * start block contiguity tests.
> +      */
> +     error = xfs_rmap_lookup_le(cur, bno, len, owner, offset, oldext, &i);
> +     if (error)
> +             goto done;
> +     XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +
> +     error = xfs_rmap_get_rec(cur, &PREV, &i);
> +     if (error)
> +             goto done;
> +     XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +     trace_xfs_rmap_lookup_le_range_result(cur->bc_mp,
> +                     cur->bc_private.a.agno, PREV.rm_startblock,
> +                     PREV.rm_blockcount, PREV.rm_owner,
> +                     PREV.rm_offset, PREV.rm_flags);
> +
> +     ASSERT(PREV.rm_offset <= offset);
> +     ASSERT(PREV.rm_offset + PREV.rm_blockcount >= new_endoff);
> +     ASSERT((PREV.rm_flags & XFS_RMAP_UNWRITTEN) == oldext);
> +     newext = ~oldext & XFS_RMAP_UNWRITTEN;
> +
> +     /*
> +      * Set flags determining what part of the previous oldext allocation
> +      * extent is being replaced by a newext allocation.
> +      */
> +     if (PREV.rm_offset == offset)
> +             state |= RMAP_LEFT_FILLING;
> +     if (PREV.rm_offset + PREV.rm_blockcount == new_endoff)
> +             state |= RMAP_RIGHT_FILLING;
> +
> +     /*
> +      * Decrement the cursor to see if we have a left-adjacent record to our
> +      * insertion point. This will give us the record for end block
> +      * contiguity tests.
> +      */
> +     error = xfs_btree_decrement(cur, 0, &i);
> +     if (error)
> +             goto done;
> +     if (i) {
> +             state |= RMAP_LEFT_VALID;
> +             error = xfs_rmap_get_rec(cur, &LEFT, &i);
> +             if (error)
> +                     goto done;
> +             XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +             XFS_WANT_CORRUPTED_GOTO(mp,
> +                             LEFT.rm_startblock + LEFT.rm_blockcount <= bno,
> +                             done);
> +             trace_xfs_rmap_find_left_neighbor_result(cur->bc_mp,
> +                             cur->bc_private.a.agno, LEFT.rm_startblock,
> +                             LEFT.rm_blockcount, LEFT.rm_owner,
> +                             LEFT.rm_offset, LEFT.rm_flags);
> +             if (LEFT.rm_startblock + LEFT.rm_blockcount == bno &&
> +                 LEFT.rm_offset + LEFT.rm_blockcount == offset &&
> +                 xfs_rmap_is_mergeable(&LEFT, owner, offset, len, newext))
> +                     state |= RMAP_LEFT_CONTIG;
> +     }
> +
> +     /*
> +      * Increment the cursor to see if we have a right-adjacent record to our
> +      * insertion point. This will give us the record for end block
> +      * contiguity tests.
> +      */
> +     error = xfs_btree_increment(cur, 0, &i);
> +     if (error)
> +             goto done;
> +     XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +     error = xfs_btree_increment(cur, 0, &i);
> +     if (error)
> +             goto done;
> +     if (i) {
> +             state |= RMAP_RIGHT_VALID;
> +             error = xfs_rmap_get_rec(cur, &RIGHT, &i);
> +             if (error)
> +                     goto done;
> +             XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +             XFS_WANT_CORRUPTED_GOTO(mp, bno + len <= RIGHT.rm_startblock,
> +                                     done);
> +             trace_xfs_rmap_convert_gtrec(cur->bc_mp,
> +                             cur->bc_private.a.agno, RIGHT.rm_startblock,
> +                             RIGHT.rm_blockcount, RIGHT.rm_owner,
> +                             RIGHT.rm_offset, RIGHT.rm_flags);
> +             if (bno + len == RIGHT.rm_startblock &&
> +                 offset + len == RIGHT.rm_offset &&
> +                 xfs_rmap_is_mergeable(&RIGHT, owner, offset, len, newext))
> +                     state |= RMAP_RIGHT_CONTIG;
> +     }
> +
> +     /* check that left + prev + right is not too long */
> +     if ((state & (RMAP_LEFT_FILLING | RMAP_LEFT_CONTIG |
> +                      RMAP_RIGHT_FILLING | RMAP_RIGHT_CONTIG)) ==
> +         (RMAP_LEFT_FILLING | RMAP_LEFT_CONTIG |
> +          RMAP_RIGHT_FILLING | RMAP_RIGHT_CONTIG) &&
> +         (unsigned long)LEFT.rm_blockcount + len +
> +          RIGHT.rm_blockcount > XFS_RMAP_LEN_MAX)
> +             state &= ~RMAP_RIGHT_CONTIG;
> +
> +     trace_xfs_rmap_convert_state(mp, cur->bc_private.a.agno, state,
> +                     _RET_IP_);
> +
> +     /* reset the cursor back to PREV */
> +     error = xfs_rmap_lookup_le(cur, bno, len, owner, offset, oldext, &i);
> +     if (error)
> +             goto done;
> +     XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +
> +     /*
> +      * Switch out based on the FILLING and CONTIG state bits.
> +      */
> +     switch (state & (RMAP_LEFT_FILLING | RMAP_LEFT_CONTIG |
> +                      RMAP_RIGHT_FILLING | RMAP_RIGHT_CONTIG)) {
> +     case RMAP_LEFT_FILLING | RMAP_LEFT_CONTIG |
> +          RMAP_RIGHT_FILLING | RMAP_RIGHT_CONTIG:
> +             /*
> +              * Setting all of a previous oldext extent to newext.
> +              * The left and right neighbors are both contiguous with new.
> +              */
> +             error = xfs_btree_increment(cur, 0, &i);
> +             if (error)
> +                     goto done;
> +             XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +             trace_xfs_rmapbt_delete(mp, cur->bc_private.a.agno,
> +                             RIGHT.rm_startblock, RIGHT.rm_blockcount,
> +                             RIGHT.rm_owner, RIGHT.rm_offset,
> +                             RIGHT.rm_flags);
> +             error = xfs_btree_delete(cur, &i);
> +             if (error)
> +                     goto done;
> +             XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +             error = xfs_btree_decrement(cur, 0, &i);
> +             if (error)
> +                     goto done;
> +             XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +             trace_xfs_rmapbt_delete(mp, cur->bc_private.a.agno,
> +                             PREV.rm_startblock, PREV.rm_blockcount,
> +                             PREV.rm_owner, PREV.rm_offset,
> +                             PREV.rm_flags);
> +             error = xfs_btree_delete(cur, &i);
> +             if (error)
> +                     goto done;
> +             XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +             error = xfs_btree_decrement(cur, 0, &i);
> +             if (error)
> +                     goto done;
> +             XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +             NEW = LEFT;
> +             NEW.rm_blockcount += PREV.rm_blockcount + RIGHT.rm_blockcount;
> +             error = xfs_rmap_update(cur, &NEW);
> +             if (error)
> +                     goto done;
> +             break;
> +
> +     case RMAP_LEFT_FILLING | RMAP_RIGHT_FILLING | RMAP_LEFT_CONTIG:
> +             /*
> +              * Setting all of a previous oldext extent to newext.
> +              * The left neighbor is contiguous, the right is not.
> +              */
> +             trace_xfs_rmapbt_delete(mp, cur->bc_private.a.agno,
> +                             PREV.rm_startblock, PREV.rm_blockcount,
> +                             PREV.rm_owner, PREV.rm_offset,
> +                             PREV.rm_flags);
> +             error = xfs_btree_delete(cur, &i);
> +             if (error)
> +                     goto done;
> +             XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +             error = xfs_btree_decrement(cur, 0, &i);
> +             if (error)
> +                     goto done;
> +             XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +             NEW = LEFT;
> +             NEW.rm_blockcount += PREV.rm_blockcount;
> +             error = xfs_rmap_update(cur, &NEW);
> +             if (error)
> +                     goto done;
> +             break;
> +
> +     case RMAP_LEFT_FILLING | RMAP_RIGHT_FILLING | RMAP_RIGHT_CONTIG:
> +             /*
> +              * Setting all of a previous oldext extent to newext.
> +              * The right neighbor is contiguous, the left is not.
> +              */
> +             error = xfs_btree_increment(cur, 0, &i);
> +             if (error)
> +                     goto done;
> +             XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +             trace_xfs_rmapbt_delete(mp, cur->bc_private.a.agno,
> +                             RIGHT.rm_startblock, RIGHT.rm_blockcount,
> +                             RIGHT.rm_owner, RIGHT.rm_offset,
> +                             RIGHT.rm_flags);
> +             error = xfs_btree_delete(cur, &i);
> +             if (error)
> +                     goto done;
> +             XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +             error = xfs_btree_decrement(cur, 0, &i);
> +             if (error)
> +                     goto done;
> +             XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +             NEW.rm_startblock = bno;
> +             NEW.rm_owner = owner;
> +             NEW.rm_offset = offset;
> +             NEW.rm_blockcount = len + RIGHT.rm_blockcount;
> +             NEW.rm_flags = newext;
> +             error = xfs_rmap_update(cur, &NEW);
> +             if (error)
> +                     goto done;
> +             break;
> +
> +     case RMAP_LEFT_FILLING | RMAP_RIGHT_FILLING:
> +             /*
> +              * Setting all of a previous oldext extent to newext.
> +              * Neither the left nor right neighbors are contiguous with
> +              * the new one.
> +              */
> +             NEW = PREV;
> +             NEW.rm_flags = newext;
> +             error = xfs_rmap_update(cur, &NEW);
> +             if (error)
> +                     goto done;
> +             break;
> +
> +     case RMAP_LEFT_FILLING | RMAP_LEFT_CONTIG:
> +             /*
> +              * Setting the first part of a previous oldext extent to newext.
> +              * The left neighbor is contiguous.
> +              */
> +             NEW = PREV;
> +             NEW.rm_offset += len;
> +             NEW.rm_startblock += len;
> +             NEW.rm_blockcount -= len;
> +             error = xfs_rmap_update(cur, &NEW);
> +             if (error)
> +                     goto done;
> +             error = xfs_btree_decrement(cur, 0, &i);
> +             if (error)
> +                     goto done;
> +             NEW = LEFT;
> +             NEW.rm_blockcount += len;
> +             error = xfs_rmap_update(cur, &NEW);
> +             if (error)
> +                     goto done;
> +             break;
> +
> +     case RMAP_LEFT_FILLING:
> +             /*
> +              * Setting the first part of a previous oldext extent to newext.
> +              * The left neighbor is not contiguous.
> +              */
> +             NEW = PREV;
> +             NEW.rm_startblock += len;
> +             NEW.rm_offset += len;
> +             NEW.rm_blockcount -= len;
> +             error = xfs_rmap_update(cur, &NEW);
> +             if (error)
> +                     goto done;
> +             NEW.rm_startblock = bno;
> +             NEW.rm_owner = owner;
> +             NEW.rm_offset = offset;
> +             NEW.rm_blockcount = len;
> +             NEW.rm_flags = newext;
> +             cur->bc_rec.r = NEW;
> +             trace_xfs_rmapbt_insert(mp, cur->bc_private.a.agno, bno,
> +                             len, owner, offset, newext);
> +             error = xfs_btree_insert(cur, &i);
> +             if (error)
> +                     goto done;
> +             XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +             break;
> +
> +     case RMAP_RIGHT_FILLING | RMAP_RIGHT_CONTIG:
> +             /*
> +              * Setting the last part of a previous oldext extent to newext.
> +              * The right neighbor is contiguous with the new allocation.
> +              */
> +             NEW = PREV;
> +             NEW.rm_blockcount -= len;
> +             error = xfs_rmap_update(cur, &NEW);
> +             if (error)
> +                     goto done;
> +             error = xfs_btree_increment(cur, 0, &i);
> +             if (error)
> +                     goto done;
> +             NEW = RIGHT;
> +             NEW.rm_offset = offset;
> +             NEW.rm_startblock = bno;
> +             NEW.rm_blockcount += len;
> +             error = xfs_rmap_update(cur, &NEW);
> +             if (error)
> +                     goto done;
> +             break;
> +
> +     case RMAP_RIGHT_FILLING:
> +             /*
> +              * Setting the last part of a previous oldext extent to newext.
> +              * The right neighbor is not contiguous.
> +              */
> +             NEW = PREV;
> +             NEW.rm_blockcount -= len;
> +             error = xfs_rmap_update(cur, &NEW);
> +             if (error)
> +                     goto done;
> +             error = xfs_rmap_lookup_eq(cur, bno, len, owner, offset,
> +                             oldext, &i);
> +             if (error)
> +                     goto done;
> +             XFS_WANT_CORRUPTED_GOTO(mp, i == 0, done);
> +             NEW.rm_startblock = bno;
> +             NEW.rm_owner = owner;
> +             NEW.rm_offset = offset;
> +             NEW.rm_blockcount = len;
> +             NEW.rm_flags = newext;
> +             cur->bc_rec.r = NEW;
> +             trace_xfs_rmapbt_insert(mp, cur->bc_private.a.agno, bno,
> +                             len, owner, offset, newext);
> +             error = xfs_btree_insert(cur, &i);
> +             if (error)
> +                     goto done;
> +             XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +             break;
> +
> +     case 0:
> +             /*
> +              * Setting the middle part of a previous oldext extent to
> +              * newext.  Contiguity is impossible here.
> +              * One extent becomes three extents.
> +              */
> +             /* new right extent - oldext */
> +             NEW.rm_startblock = bno + len;
> +             NEW.rm_owner = owner;
> +             NEW.rm_offset = new_endoff;
> +             NEW.rm_blockcount = PREV.rm_offset + PREV.rm_blockcount -
> +                             new_endoff;
> +             NEW.rm_flags = PREV.rm_flags;
> +             error = xfs_rmap_update(cur, &NEW);
> +             if (error)
> +                     goto done;
> +             /* new left extent - oldext */
> +             NEW = PREV;
> +             NEW.rm_blockcount = offset - PREV.rm_offset;
> +             cur->bc_rec.r = NEW;
> +             trace_xfs_rmapbt_insert(mp, cur->bc_private.a.agno,
> +                             NEW.rm_startblock, NEW.rm_blockcount,
> +                             NEW.rm_owner, NEW.rm_offset,
> +                             NEW.rm_flags);
> +             error = xfs_btree_insert(cur, &i);
> +             if (error)
> +                     goto done;
> +             XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +             /*
> +              * Reset the cursor to the position of the new extent
> +              * we are about to insert as we can't trust it after
> +              * the previous insert.
> +              */
> +             error = xfs_rmap_lookup_eq(cur, bno, len, owner, offset,
> +                             oldext, &i);
> +             if (error)
> +                     goto done;
> +             XFS_WANT_CORRUPTED_GOTO(mp, i == 0, done);
> +             /* new middle extent - newext */
> +             cur->bc_rec.b.br_state = newext;

Wrong, should be:

                cur->bc_rec.r.rm_flags &= ~XFS_RMAP_UNWRITTEN;
                cur->bc_rec.r.rm_flags |= newext;

We're modifying the rmapbt here, not the bmbt, so it makes no sense to touch
the bmbt_irec in the cursor.  Modify the rmap_irec instead.  Incidentally
this just happens not to fail because the fields line up....

--D

> +             trace_xfs_rmapbt_insert(mp, cur->bc_private.a.agno, bno, len,
> +                             owner, offset, newext);
> +             error = xfs_btree_insert(cur, &i);
> +             if (error)
> +                     goto done;
> +             XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
> +             break;
> +
> +     case RMAP_LEFT_FILLING | RMAP_LEFT_CONTIG | RMAP_RIGHT_CONTIG:
> +     case RMAP_RIGHT_FILLING | RMAP_LEFT_CONTIG | RMAP_RIGHT_CONTIG:
> +     case RMAP_LEFT_FILLING | RMAP_RIGHT_CONTIG:
> +     case RMAP_RIGHT_FILLING | RMAP_LEFT_CONTIG:
> +     case RMAP_LEFT_CONTIG | RMAP_RIGHT_CONTIG:
> +     case RMAP_LEFT_CONTIG:
> +     case RMAP_RIGHT_CONTIG:
> +             /*
> +              * These cases are all impossible.
> +              */
> +             ASSERT(0);
> +     }
> +
> +     trace_xfs_rmap_convert_done(mp, cur->bc_private.a.agno, bno, len,
> +                     unwritten, oinfo);
> +done:
> +     if (error)
> +             trace_xfs_rmap_convert_error(cur->bc_mp,
> +                             cur->bc_private.a.agno, error, _RET_IP_);
> +     return error;
> +}
> +
> +#undef       NEW
> +#undef       LEFT
> +#undef       RIGHT
> +#undef       PREV
> +
>  struct xfs_rmapbt_query_range_info {
>       xfs_rmapbt_query_range_fn       fn;
>       void                            *priv;
> diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
> index 3ebceb0..6466adc 100644
> --- a/fs/xfs/xfs_trace.h
> +++ b/fs/xfs/xfs_trace.h
> @@ -2497,6 +2497,10 @@ DEFINE_RMAP_EVENT(xfs_rmap_free_extent_error);
>  DEFINE_RMAP_EVENT(xfs_rmap_alloc_extent);
>  DEFINE_RMAP_EVENT(xfs_rmap_alloc_extent_done);
>  DEFINE_RMAP_EVENT(xfs_rmap_alloc_extent_error);
> +DEFINE_RMAP_EVENT(xfs_rmap_convert);
> +DEFINE_RMAP_EVENT(xfs_rmap_convert_done);
> +DEFINE_AG_ERROR_EVENT(xfs_rmap_convert_error);
> +DEFINE_AG_ERROR_EVENT(xfs_rmap_convert_state);
>  
>  DECLARE_EVENT_CLASS(xfs_rmapbt_class,
>       TP_PROTO(struct xfs_mount *mp, xfs_agnumber_t agno,
> @@ -2551,6 +2555,8 @@ DEFINE_AG_ERROR_EVENT(xfs_rmapbt_delete_error);
>  DEFINE_AG_ERROR_EVENT(xfs_rmapbt_update_error);
>  DEFINE_RMAPBT_EVENT(xfs_rmap_lookup_le_range_result);
>  DEFINE_RMAPBT_EVENT(xfs_rmap_map_gtrec);
> +DEFINE_RMAPBT_EVENT(xfs_rmap_convert_gtrec);
> +DEFINE_RMAPBT_EVENT(xfs_rmap_find_left_neighbor_result);
>  
>  #endif /* _TRACE_XFS_H */
>  
> 
> _______________________________________________
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> xfs@xxxxxxxxxxx
> http://oss.sgi.com/mailman/listinfo/xfs

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