On Sunday 25 October 2020 6:52:53 AM IST Allison Henderson wrote: > > On 10/18/20 11:40 PM, Chandan Babu R wrote: > > This commit adds XFS_ERRTAG_BMAP_ALLOC_MINLEN_EXTENT error tag which > > helps userspace test programs to get xfs_bmap_btalloc() to always > > allocate minlen sized extents. > > > > This is required for test programs which need a guarantee that minlen > > extents allocated for a file do not get merged with their existing > > neighbours in the inode's BMBT. "Inode fork extent overflow check" for > > Directories, Xattrs and extension of realtime inodes need this since the > > file offset at which the extents are being allocated cannot be > > explicitly controlled from userspace. > > > > One way to use this error tag is to, > > 1. Consume all of the free space by sequentially writing to a file. > > 2. Punch alternate blocks of the file. This causes CNTBT to contain > > sufficient number of one block sized extent records. > > 3. Inject XFS_ERRTAG_BMAP_ALLOC_MINLEN_EXTENT error tag. > > After step 3, xfs_bmap_btalloc() will issue space allocation > > requests for minlen sized extents only. > > > > ENOSPC error code is returned to userspace when there aren't any "one > > block sized" extents left in any of the AGs. > > > > Signed-off-by: Chandan Babu R <chandanrlinux@xxxxxxxxx> > > --- > > fs/xfs/libxfs/xfs_alloc.c | 50 ++++++++++++++++++ > > fs/xfs/libxfs/xfs_alloc.h | 3 ++ > > fs/xfs/libxfs/xfs_bmap.c | 100 +++++++++++++++++++++++++++++++---- > > fs/xfs/libxfs/xfs_errortag.h | 4 +- > > fs/xfs/xfs_error.c | 3 ++ > > 5 files changed, 150 insertions(+), 10 deletions(-) > > > > diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c > > index 852b536551b5..8e132f8b9cc4 100644 > > --- a/fs/xfs/libxfs/xfs_alloc.c > > +++ b/fs/xfs/libxfs/xfs_alloc.c > > @@ -2473,6 +2473,47 @@ xfs_defer_agfl_block( > > xfs_defer_add(tp, XFS_DEFER_OPS_TYPE_AGFL_FREE, &new->xefi_list); > > } > > > > +#ifdef DEBUG > > +/* > > + * Check if an AGF has a free extent record whose length is equal to > > + * args->minlen. > > + */ > > +STATIC int > > +xfs_exact_minlen_extent_available( > > + struct xfs_alloc_arg *args, > > + struct xfs_buf *agbp, > > + int *stat) > > +{ > > + struct xfs_btree_cur *cnt_cur; > > + xfs_agblock_t fbno; > > + xfs_extlen_t flen; > > + int error = 0; > > + > > + cnt_cur = xfs_allocbt_init_cursor(args->mp, args->tp, agbp, > > + args->agno, XFS_BTNUM_CNT); > > + error = xfs_alloc_lookup_ge(cnt_cur, 0, args->minlen, stat); > > + if (error) > > + goto out; > > + > > + if (*stat == 0) { > > + error = -EFSCORRUPTED; > > + goto out; > > + } > > + > > + error = xfs_alloc_get_rec(cnt_cur, &fbno, &flen, stat); > > + if (error) > > + goto out; > > + > > + if (*stat == 1 && flen != args->minlen) > > + *stat = 0; > > + > > +out: > > + xfs_btree_del_cursor(cnt_cur, error); > > + > > + return error; > > +} > > +#endif > > + > > /* > > * Decide whether to use this allocation group for this allocation. > > * If so, fix up the btree freelist's size. > > @@ -2544,6 +2585,15 @@ xfs_alloc_fix_freelist( > > if (!xfs_alloc_space_available(args, need, flags)) > > goto out_agbp_relse; > > > > +#ifdef DEBUG > > + if (args->alloc_minlen_only) { > > + int i; > Just a nit: I think "i" seems like a bit of an odd name here. I think I > might have called it stat to match its parameter name. Other than that, > I think the rest looks ok. Ok, I will rename "i" with "stat" as you have suggested. Thank you for reviewing the patchset. > > Reviewed-by: Allison Henderson <allison.henderson@xxxxxxxxxx> > Allison > > + > > + error = xfs_exact_minlen_extent_available(args, agbp, &i); > > + if (error || !i) > > + goto out_agbp_relse; > > + } > > +#endif > > /* > > * Make the freelist shorter if it's too long. > > * > > diff --git a/fs/xfs/libxfs/xfs_alloc.h b/fs/xfs/libxfs/xfs_alloc.h > > index 6c22b12176b8..a4427c5775c2 100644 > > --- a/fs/xfs/libxfs/xfs_alloc.h > > +++ b/fs/xfs/libxfs/xfs_alloc.h > > @@ -75,6 +75,9 @@ typedef struct xfs_alloc_arg { > > char wasfromfl; /* set if allocation is from freelist */ > > struct xfs_owner_info oinfo; /* owner of blocks being allocated */ > > enum xfs_ag_resv_type resv; /* block reservation to use */ > > +#ifdef DEBUG > > + bool alloc_minlen_only; /* allocate exact minlen extent */ > > +#endif > > } xfs_alloc_arg_t; > > > > /* > > diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c > > index 88db23afc51c..74e148cc41b2 100644 > > --- a/fs/xfs/libxfs/xfs_bmap.c > > +++ b/fs/xfs/libxfs/xfs_bmap.c > > @@ -3474,11 +3474,13 @@ xfs_bmap_compute_alignments( > > int error; > > > > /* stripe alignment for allocation is determined by mount parameters */ > > - *stripe_align = 0; > > - if (mp->m_swidth && (mp->m_flags & XFS_MOUNT_SWALLOC)) > > - *stripe_align = mp->m_swidth; > > - else if (mp->m_dalign) > > - *stripe_align = mp->m_dalign; > > + if (stripe_align) { > > + *stripe_align = 0; > > + if (mp->m_swidth && (mp->m_flags & XFS_MOUNT_SWALLOC)) > > + *stripe_align = mp->m_swidth; > > + else if (mp->m_dalign) > > + *stripe_align = mp->m_dalign; > > + } > > > > if (ap->flags & XFS_BMAPI_COWFORK) > > align = xfs_get_cowextsz_hint(ap->ip); > > @@ -3551,6 +3553,71 @@ xfs_bmap_process_allocated_extent( > > xfs_bmap_btalloc_accounting(ap, args); > > } > > > > +#ifdef DEBUG > > +static int > > +xfs_bmap_exact_minlen_extent_alloc( > > + struct xfs_bmalloca *ap) > > +{ > > + struct xfs_alloc_arg args; > > + struct xfs_mount *mp = ap->ip->i_mount; > > + xfs_fileoff_t orig_offset; > > + xfs_extlen_t orig_length; > > + int error; > > + > > + ASSERT(ap->length); > > + orig_offset = ap->offset; > > + orig_length = ap->length; > > + > > + memset(&args, 0, sizeof(args)); > > + args.alloc_minlen_only = 1; > > + args.tp = ap->tp; > > + args.mp = mp; > > + > > + xfs_bmap_compute_alignments(ap, &args, NULL); > > + > > + if (ap->tp->t_firstblock == NULLFSBLOCK) { > > + /* > > + * Unlike the longest extent available in an AG, we don't track > > + * the length of an AG's shortest extent. > > + * XFS_ERRTAG_BMAP_ALLOC_MINLEN_EXTENT is a debug only knob and > > + * hence we can afford to start traversing from the 0th AG since > > + * we need not be concerned about a drop in performance in > > + * "debug only" code paths. > > + */ > > + ap->blkno = XFS_AGB_TO_FSB(mp, 0, 0); > > + } else { > > + ap->blkno = ap->tp->t_firstblock; > > + } > > + > > + args.fsbno = ap->blkno; > > + args.oinfo = XFS_RMAP_OINFO_SKIP_UPDATE; > > + args.type = XFS_ALLOCTYPE_FIRST_AG; > > + args.total = args.minlen = args.maxlen = ap->minlen; > > + > > + args.alignment = 1; > > + args.minalignslop = 0; > > + > > + args.minleft = ap->minleft; > > + args.wasdel = ap->wasdel; > > + args.resv = XFS_AG_RESV_NONE; > > + args.datatype = ap->datatype; > > + > > + error = xfs_alloc_vextent(&args); > > + if (error) > > + return error; > > + > > + if (args.fsbno != NULLFSBLOCK) { > > + xfs_bmap_process_allocated_extent(ap, &args, orig_offset, > > + orig_length); > > + } else { > > + ap->blkno = NULLFSBLOCK; > > + ap->length = 0; > > + } > > + > > + return 0; > > +} > > +#endif > > + > > STATIC int > > xfs_bmap_btalloc( > > struct xfs_bmalloca *ap) /* bmap alloc argument struct */ > > @@ -4112,7 +4179,13 @@ xfs_bmap_alloc_userdata( > > return xfs_bmap_rtalloc(bma); > > } > > > > - return xfs_bmap_btalloc(bma); > > +#ifdef DEBUG > > + if (unlikely(XFS_TEST_ERROR(false, mp, > > + XFS_ERRTAG_BMAP_ALLOC_MINLEN_EXTENT))) > > + return xfs_bmap_exact_minlen_extent_alloc(bma); > > + else > > +#endif > > + return xfs_bmap_btalloc(bma); > > } > > > > static int > > @@ -4148,10 +4221,19 @@ xfs_bmapi_allocate( > > else > > bma->minlen = 1; > > > > - if (bma->flags & XFS_BMAPI_METADATA) > > - error = xfs_bmap_btalloc(bma); > > - else > > + if (bma->flags & XFS_BMAPI_METADATA) { > > +#ifdef DEBUG > > + if (unlikely(XFS_TEST_ERROR(false, mp, > > + XFS_ERRTAG_BMAP_ALLOC_MINLEN_EXTENT))) > > + error = xfs_bmap_exact_minlen_extent_alloc(bma); > > + else > > +#endif > > + error = xfs_bmap_btalloc(bma); > > + > > + > > + } else { > > error = xfs_bmap_alloc_userdata(bma); > > + } > > if (error || bma->blkno == NULLFSBLOCK) > > return error; > > > > diff --git a/fs/xfs/libxfs/xfs_errortag.h b/fs/xfs/libxfs/xfs_errortag.h > > index 1c56fcceeea6..6ca9084b6934 100644 > > --- a/fs/xfs/libxfs/xfs_errortag.h > > +++ b/fs/xfs/libxfs/xfs_errortag.h > > @@ -57,7 +57,8 @@ > > #define XFS_ERRTAG_IUNLINK_FALLBACK 34 > > #define XFS_ERRTAG_BUF_IOERROR 35 > > #define XFS_ERRTAG_REDUCE_MAX_IEXTENTS 36 > > -#define XFS_ERRTAG_MAX 37 > > +#define XFS_ERRTAG_BMAP_ALLOC_MINLEN_EXTENT 37 > > +#define XFS_ERRTAG_MAX 38 > > > > /* > > * Random factors for above tags, 1 means always, 2 means 1/2 time, etc. > > @@ -99,5 +100,6 @@ > > #define XFS_RANDOM_IUNLINK_FALLBACK (XFS_RANDOM_DEFAULT/10) > > #define XFS_RANDOM_BUF_IOERROR XFS_RANDOM_DEFAULT > > #define XFS_RANDOM_REDUCE_MAX_IEXTENTS 1 > > +#define XFS_RANDOM_BMAP_ALLOC_MINLEN_EXTENT 1 > > > > #endif /* __XFS_ERRORTAG_H_ */ > > diff --git a/fs/xfs/xfs_error.c b/fs/xfs/xfs_error.c > > index 3780b118cc47..185b4915b7bf 100644 > > --- a/fs/xfs/xfs_error.c > > +++ b/fs/xfs/xfs_error.c > > @@ -55,6 +55,7 @@ static unsigned int xfs_errortag_random_default[] = { > > XFS_RANDOM_IUNLINK_FALLBACK, > > XFS_RANDOM_BUF_IOERROR, > > XFS_RANDOM_REDUCE_MAX_IEXTENTS, > > + XFS_RANDOM_BMAP_ALLOC_MINLEN_EXTENT, > > }; > > > > struct xfs_errortag_attr { > > @@ -166,6 +167,7 @@ XFS_ERRORTAG_ATTR_RW(bad_summary, XFS_ERRTAG_FORCE_SUMMARY_RECALC); > > XFS_ERRORTAG_ATTR_RW(iunlink_fallback, XFS_ERRTAG_IUNLINK_FALLBACK); > > XFS_ERRORTAG_ATTR_RW(buf_ioerror, XFS_ERRTAG_BUF_IOERROR); > > XFS_ERRORTAG_ATTR_RW(reduce_max_iextents, XFS_ERRTAG_REDUCE_MAX_IEXTENTS); > > +XFS_ERRORTAG_ATTR_RW(bmap_alloc_minlen_extent, XFS_ERRTAG_BMAP_ALLOC_MINLEN_EXTENT); > > > > static struct attribute *xfs_errortag_attrs[] = { > > XFS_ERRORTAG_ATTR_LIST(noerror), > > @@ -205,6 +207,7 @@ static struct attribute *xfs_errortag_attrs[] = { > > XFS_ERRORTAG_ATTR_LIST(iunlink_fallback), > > XFS_ERRORTAG_ATTR_LIST(buf_ioerror), > > XFS_ERRORTAG_ATTR_LIST(reduce_max_iextents), > > + XFS_ERRORTAG_ATTR_LIST(bmap_alloc_minlen_extent), > > NULL, > > }; > > > > > -- chandan