Create the refcount btree at mkfs time and set the feature flag.
v2: Turn on the reflink feature when calculating the minimum log size.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
include/xfs_multidisk.h | 3 +-
man/man8/mkfs.xfs.8 | 28 ++++++++++++++++++++
mkfs/maxtrres.c | 5 +++-
mkfs/xfs_mkfs.c | 67 +++++++++++++++++++++++++++++++++++++++++++----
4 files changed, 95 insertions(+), 8 deletions(-)
diff --git a/include/xfs_multidisk.h b/include/xfs_multidisk.h
index 8dc3027..ce9bbce 100644
--- a/include/xfs_multidisk.h
+++ b/include/xfs_multidisk.h
@@ -68,6 +68,7 @@ extern void res_failed (int err);
/* maxtrres.c */
extern int max_trans_res(unsigned long agsize, int crcs_enabled, int dirversion,
int sectorlog, int blocklog, int inodelog, int dirblocklog,
- int logversion, int log_sunit, int finobt, int rmapbt);
+ int logversion, int log_sunit, int finobt, int rmapbt,
+ int reflink);
#endif /* __XFS_MULTIDISK_H__ */
diff --git a/man/man8/mkfs.xfs.8 b/man/man8/mkfs.xfs.8
index d88d314..6131e24 100644
--- a/man/man8/mkfs.xfs.8
+++ b/man/man8/mkfs.xfs.8
@@ -213,6 +213,34 @@ for filesystems created with the (default)
option set. When the option
.B \-m crc=0
is used, the reverse mapping btree feature is not supported and is disabled.
+.TP
+.BI reflink= value
+This option enables the use of a separate reference count btree index in each
+allocation group. The value is either 0 to disable the feature, or 1 to create
+a reference count btree in each allocation group.
+.IP
+The reference count btree enables the sharing of physical extents between
+the data forks of different files, which is commonly known as "reflink".
+Unlike traditional Unix filesystems which assume that every inode and
+logical block pair map to a unique physical block, a reflink-capable
+XFS filesystem removes the uniqueness requirement, allowing up to four
+billion arbitrary inode/logical block pairs to map to a physical block.
+If a program tries to write to a multiply-referenced block in a file, the write
+will be redirected to a new block, and that file's logical-to-physical
+mapping will be changed to the new block ("copy on write"). This feature
+enables the creation of per-file snapshots and deduplication. It is only
+available for the data forks of regular files.
+.IP
+By default,
+.B mkfs.xfs
+will not create reference count btrees and therefore will not enable the
+reflink feature. This feature is only available for filesystems created with
+the (default)
+.B \-m crc=1
+option set. When the option
+.B \-m crc=0
+is used, the reference count btree feature is not supported and reflink is
+disabled.
.RE
.TP
.BI \-d " data_section_options"
diff --git a/mkfs/maxtrres.c b/mkfs/maxtrres.c
index fc24eac..a9c0985 100644
--- a/mkfs/maxtrres.c
+++ b/mkfs/maxtrres.c
@@ -39,7 +39,8 @@ max_trans_res(
int logversion,
int log_sunit,
int finobt,
- int rmapbt)
+ int rmapbt,
+ int reflink)
{
xfs_sb_t *sbp;
xfs_mount_t mount;
@@ -75,6 +76,8 @@ max_trans_res(
sbp->sb_features_ro_compat |= XFS_SB_FEAT_RO_COMPAT_FINOBT;
if (rmapbt)
sbp->sb_features_ro_compat |= XFS_SB_FEAT_RO_COMPAT_RMAPBT;
+ if (reflink)
+ sbp->sb_features_ro_compat |= XFS_SB_FEAT_RO_COMPAT_REFLINK;
libxfs_mount(&mount, sbp, 0,0,0,0);
maxfsb = xfs_log_calc_minimum_size(&mount);
diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
index 634dcfd..3753731 100644
--- a/mkfs/xfs_mkfs.c
+++ b/mkfs/xfs_mkfs.c
@@ -682,6 +682,8 @@ struct opt_params mopts = {
"uuid",
#define M_RMAPBT 3
"rmapbt",
+#define M_REFLINK 4
+ "reflink",
NULL
},
.subopt_params = {
@@ -707,6 +709,12 @@ struct opt_params mopts = {
.maxval = 1,
.defaultval = 0,
},
+ { .index = M_REFLINK,
+ .conflicts = { LAST_CONFLICT },
+ .minval = 0,
+ .maxval = 1,
+ .defaultval = 0,
+ },
},
};
@@ -1463,6 +1471,7 @@ struct sb_feat_args {
bool dirftype;
bool parent_pointers;
bool rmapbt;
+ bool reflink;
};
static void
@@ -1535,6 +1544,8 @@ sb_set_features(
sbp->sb_features_ro_compat = XFS_SB_FEAT_RO_COMPAT_FINOBT;
if (fp->rmapbt)
sbp->sb_features_ro_compat |= XFS_SB_FEAT_RO_COMPAT_RMAPBT;
+ if (fp->reflink)
+ sbp->sb_features_ro_compat |= XFS_SB_FEAT_RO_COMPAT_REFLINK;
/*
* Sparse inode chunk support has two main inode alignment requirements.
@@ -1796,6 +1807,7 @@ main(
.dirftype = true,
.parent_pointers = false,
.rmapbt = false,
+ .reflink = false,
};
platform_uuid_generate(&uuid);
@@ -2089,6 +2101,10 @@ main(
sb_feat.rmapbt = getnum(
value, &mopts, M_RMAPBT);
break;
+ case M_REFLINK:
+ sb_feat.reflink = getnum(
+ value, &mopts, M_REFLINK);
+ break;
default:
unknown('m', value);
}
@@ -2431,6 +2447,13 @@ _("rmapbt not supported without CRC support\n"));
usage();
}
sb_feat.rmapbt = false;
+
+ if (sb_feat.reflink) {
+ fprintf(stderr,
+_("reflink not supported without CRC support\n"));
+ usage();
+ }
+ sb_feat.reflink = false;
}
@@ -2921,7 +2944,7 @@ an AG size that is one stripe unit smaller, for example %llu.\n"),
sb_feat.crcs_enabled, sb_feat.dir_version,
sectorlog, blocklog, inodelog, dirblocklog,
sb_feat.log_version, lsunit, sb_feat.finobt,
- sb_feat.rmapbt);
+ sb_feat.rmapbt, sb_feat.reflink);
ASSERT(min_logblocks);
min_logblocks = MAX(XFS_MIN_LOG_BLOCKS, min_logblocks);
if (!logsize && dblocks >= (1024*1024*1024) >> blocklog)
@@ -3056,7 +3079,7 @@ _("size %s specified for log subvolume is too large, maximum is %lld blocks\n"),
printf(_(
"meta-data=%-22s isize=%-6d agcount=%lld, agsize=%lld blks\n"
" =%-22s sectsz=%-5u attr=%u, projid32bit=%u\n"
- " =%-22s crc=%-8u finobt=%u, sparse=%u, rmapbt=%u\n"
+ " =%-22s crc=%-8u finobt=%u, sparse=%u, rmapbt=%u, reflink=%u\n"
"data =%-22s bsize=%-6u blocks=%llu, imaxpct=%u\n"
" =%-22s sunit=%-6u swidth=%u blks\n"
"naming =version %-14u bsize=%-6u ascii-ci=%d ftype=%d\n"
@@ -3067,7 +3090,7 @@ _("size %s specified for log subvolume is too large, maximum is %lld blocks\n"),
"", sectorsize, sb_feat.attr_version,
!sb_feat.projid16bit,
"", sb_feat.crcs_enabled, sb_feat.finobt, sb_feat.spinodes,
- sb_feat.rmapbt,
+ sb_feat.rmapbt, sb_feat.reflink,
"", blocksize, (long long)dblocks, imaxpct,
"", dsunit, dswidth,
sb_feat.dir_version, dirblocksize, sb_feat.nci,
@@ -3254,7 +3277,10 @@ _("size %s specified for log subvolume is too large, maximum is %lld blocks\n"),
cpu_to_be32(XFS_RMAP_BLOCK(mp));
agf->agf_levels[XFS_BTNUM_RMAPi] = cpu_to_be32(1);
}
-
+ if (xfs_sb_version_hasreflink(&mp->m_sb)) {
+ agf->agf_refcount_root = cpu_to_be32(xfs_refc_block(mp));
+ agf->agf_refcount_level = cpu_to_be32(1);
+ }
agf->agf_flfirst = 0;
agf->agf_fllast = cpu_to_be32(XFS_AGFL_SIZE(mp) - 1);
agf->agf_flcount = 0;
@@ -3423,6 +3449,23 @@ _("size %s specified for log subvolume is too large, maximum is %lld blocks\n"),
libxfs_writebuf(buf, LIBXFS_EXIT_ON_FAILURE);
/*
+ * refcount btree root block
+ */
+ if (xfs_sb_version_hasreflink(&mp->m_sb)) {
+ buf = libxfs_getbuf(mp->m_ddev_targp,
+ XFS_AGB_TO_DADDR(mp, agno, xfs_refc_block(mp)),
+ bsize);
+ buf->b_ops = &xfs_refcountbt_buf_ops;
+
+ block = XFS_BUF_TO_BLOCK(buf);
+ memset(block, 0, blocksize);
+ xfs_btree_init_block(mp, buf, XFS_REFC_CRC_MAGIC, 0, 0,
+ agno, XFS_BTREE_CRC_BLOCKS);
+
+ libxfs_writebuf(buf, LIBXFS_EXIT_ON_FAILURE);
+ }
+
+ /*
* INO btree root block
*/
buf = libxfs_getbuf(mp->m_ddev_targp,
@@ -3510,9 +3553,21 @@ _("size %s specified for log subvolume is too large, maximum is %lld blocks\n"),
rrec->rm_offset = 0;
be16_add_cpu(&block->bb_numrecs, 1);
+ /* account for refcount btree root */
+ if (xfs_sb_version_hasreflink(&mp->m_sb)) {
+ rrec = XFS_RMAP_REC_ADDR(block, 5);
+ rrec->rm_startblock = cpu_to_be32(
+ xfs_refc_block(mp));
+ rrec->rm_blockcount = cpu_to_be32(1);
+ rrec->rm_owner = cpu_to_be64(XFS_RMAP_OWN_REFC);
+ rrec->rm_offset = 0;
+ be16_add_cpu(&block->bb_numrecs, 1);
+ }
+
/* account for the log space */
if (loginternal && agno == logagno) {
- rrec = XFS_RMAP_REC_ADDR(block, 5);
+ rrec = XFS_RMAP_REC_ADDR(block,
+ be16_to_cpu(block->bb_numrecs) + 1);
rrec->rm_startblock = cpu_to_be32(
XFS_FSB_TO_AGBNO(mp, logstart));
rrec->rm_blockcount = cpu_to_be32(logblocks);
@@ -3748,7 +3803,7 @@ usage( void )
{
fprintf(stderr, _("Usage: %s\n\
/* blocksize */ [-b log=n|size=num]\n\
-/* metadata */ [-m crc=0|1,finobt=0|1,uuid=xxx,rmapbt=0|1]\n\
+/* metadata */ [-m crc=0|1,finobt=0|1,uuid=xxx,rmapbt=0|1,reflink=0|1]\n\
/* data subvol */ [-d agcount=n,agsize=n,file,name=xxx,size=num,\n\
(sunit=value,swidth=value|su=num,sw=num|noalign),\n\
sectlog=n|sectsize=num\n\
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