Teach xfs_getbmapx how to report shared extents and CoW fork contents
accurately in the bmap output by querying the refcount btree
appropriately.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
fs/xfs/libxfs/xfs_fs.h | 4 +
fs/xfs/xfs_bmap_util.c | 146 +++++++++++++++++++++++++++++++++++++++++++-----
2 files changed, 135 insertions(+), 15 deletions(-)
diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
index 6f4f2c3..3d1efe5 100644
--- a/fs/xfs/libxfs/xfs_fs.h
+++ b/fs/xfs/libxfs/xfs_fs.h
@@ -81,14 +81,16 @@ struct getbmapx {
#define BMV_IF_PREALLOC 0x4 /* rtn status BMV_OF_PREALLOC if req */
#define BMV_IF_DELALLOC 0x8 /* rtn status BMV_OF_DELALLOC if req */
#define BMV_IF_NO_HOLES 0x10 /* Do not return holes */
+#define BMV_IF_COWFORK 0x20 /* return CoW fork rather than data */
#define BMV_IF_VALID \
(BMV_IF_ATTRFORK|BMV_IF_NO_DMAPI_READ|BMV_IF_PREALLOC| \
- BMV_IF_DELALLOC|BMV_IF_NO_HOLES)
+ BMV_IF_DELALLOC|BMV_IF_NO_HOLES|BMV_IF_COWFORK)
/* bmv_oflags values - returned for each non-header segment */
#define BMV_OF_PREALLOC 0x1 /* segment = unwritten pre-allocation */
#define BMV_OF_DELALLOC 0x2 /* segment = delayed allocation */
#define BMV_OF_LAST 0x4 /* segment is the last in the file */
+#define BMV_OF_SHARED 0x8 /* segment shared with another file */
/*
* Structure for XFS_IOC_FSSETDM.
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index e827d65..6a95a3a 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -42,6 +42,9 @@
#include "xfs_icache.h"
#include "xfs_log.h"
#include "xfs_rmap_btree.h"
+#include "xfs_iomap.h"
+#include "xfs_reflink.h"
+#include "xfs_refcount.h"
/* Kernel only BMAP related definitions and functions */
@@ -389,11 +392,13 @@ xfs_bmap_count_blocks(
STATIC int
xfs_getbmapx_fix_eof_hole(
xfs_inode_t *ip, /* xfs incore inode pointer */
+ int whichfork,
struct getbmapx *out, /* output structure */
int prealloced, /* this is a file with
* preallocated data space */
__int64_t end, /* last block requested */
- xfs_fsblock_t startblock)
+ xfs_fsblock_t startblock,
+ bool moretocome)
{
__int64_t fixlen;
xfs_mount_t *mp; /* file system mount point */
@@ -418,8 +423,9 @@ xfs_getbmapx_fix_eof_hole(
else
out->bmv_block = xfs_fsb_to_db(ip, startblock);
fileblock = XFS_BB_TO_FSB(ip->i_mount, out->bmv_offset);
- ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
- if (xfs_iext_bno_to_ext(ifp, fileblock, &lastx) &&
+ ifp = XFS_IFORK_PTR(ip, whichfork);
+ if (!moretocome &&
+ xfs_iext_bno_to_ext(ifp, fileblock, &lastx) &&
(lastx == (ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t))-1))
out->bmv_oflags |= BMV_OF_LAST;
}
@@ -427,6 +433,73 @@ xfs_getbmapx_fix_eof_hole(
return 1;
}
+/* Adjust the reported bmap around shared/unshared extent transitions. */
+STATIC int
+xfs_getbmap_adjust_shared(
+ struct xfs_inode *ip,
+ int whichfork,
+ struct xfs_bmbt_irec *map,
+ struct getbmapx *out,
+ struct xfs_bmbt_irec *next_map)
+{
+ struct xfs_mount *mp = ip->i_mount;
+ xfs_agnumber_t agno;
+ xfs_agblock_t agbno;
+ xfs_agblock_t ebno;
+ xfs_extlen_t elen;
+ xfs_extlen_t nlen;
+ int error;
+
+ next_map->br_blockcount = 0;
+
+ /* Only written data blocks can be shared. */
+ if (!xfs_is_reflink_inode(ip) || whichfork != XFS_DATA_FORK ||
+ map->br_startblock == DELAYSTARTBLOCK ||
+ map->br_startblock == HOLESTARTBLOCK ||
+ ISUNWRITTEN(map))
+ return 0;
+
+ agno = XFS_FSB_TO_AGNO(mp, map->br_startblock);
+ agbno = XFS_FSB_TO_AGBNO(mp, map->br_startblock);
+ error = xfs_reflink_find_shared(mp, agno, agbno, map->br_blockcount,
+ &ebno, &elen, true);
+ if (error)
+ return error;
+
+ *next_map = *map;
+ if (agbno == ebno) {
+ /*
+ * Shared extent at (agbno, elen). Shrink the reported
+ * extent length and prepare to move the start of map[i]
+ * to agbno+elen, with the aim of (re)formatting the new
+ * map[i] the next time through the inner loop.
+ */
+ out->bmv_length = XFS_FSB_TO_BB(mp, elen);
+ out->bmv_oflags |= BMV_OF_SHARED;
+ next_map->br_startblock += elen;
+ next_map->br_startoff += elen;
+ next_map->br_blockcount -= elen;
+ map->br_blockcount -= elen;
+ } else {
+ /*
+ * There's an unshared extent (agbno, ebno - agbno)
+ * followed by shared extent at (ebno, elen). Shrink
+ * the reported extent length to cover only the unshared
+ * extent and prepare to move up the start of map[i] to
+ * ebno, with the aim of (re)formatting the new map[i]
+ * the next time through the inner loop.
+ */
+ nlen = ebno - agbno;
+ out->bmv_length = XFS_FSB_TO_BB(mp, nlen);
+ next_map->br_startblock += nlen;
+ next_map->br_startoff += nlen;
+ next_map->br_blockcount -= nlen;
+ map->br_blockcount -= nlen;
+ }
+
+ return 0;
+}
+
/*
* Get inode's extents as described in bmv, and format for output.
* Calls formatter to fill the user's buffer until all extents
@@ -459,12 +532,28 @@ xfs_getbmap(
int iflags; /* interface flags */
int bmapi_flags; /* flags for xfs_bmapi */
int cur_ext = 0;
+ struct xfs_bmbt_irec inject_map;
mp = ip->i_mount;
iflags = bmv->bmv_iflags;
- whichfork = iflags & BMV_IF_ATTRFORK ? XFS_ATTR_FORK : XFS_DATA_FORK;
- if (whichfork == XFS_ATTR_FORK) {
+#ifndef DEBUG
+ /* Only allow CoW fork queries if we're debugging. */
+ if (iflags & BMV_IF_COWFORK)
+ return -EINVAL;
+#endif
+ if ((iflags & BMV_IF_ATTRFORK) && (iflags & BMV_IF_COWFORK))
+ return -EINVAL;
+
+ if (iflags & BMV_IF_ATTRFORK)
+ whichfork = XFS_ATTR_FORK;
+ else if (iflags & BMV_IF_COWFORK)
+ whichfork = XFS_COW_FORK;
+ else
+ whichfork = XFS_DATA_FORK;
+
+ switch (whichfork) {
+ case XFS_ATTR_FORK:
if (XFS_IFORK_Q(ip)) {
if (ip->i_d.di_aformat != XFS_DINODE_FMT_EXTENTS &&
ip->i_d.di_aformat != XFS_DINODE_FMT_BTREE &&
@@ -480,7 +569,15 @@ xfs_getbmap(
prealloced = 0;
fixlen = 1LL << 32;
- } else {
+ break;
+ case XFS_COW_FORK:
+ if (ip->i_cformat != XFS_DINODE_FMT_EXTENTS)
+ return -EINVAL;
+
+ prealloced = 0;
+ fixlen = XFS_ISIZE(ip);
+ break;
+ default:
if (ip->i_d.di_format != XFS_DINODE_FMT_EXTENTS &&
ip->i_d.di_format != XFS_DINODE_FMT_BTREE &&
ip->i_d.di_format != XFS_DINODE_FMT_LOCAL)
@@ -494,6 +591,7 @@ xfs_getbmap(
prealloced = 0;
fixlen = XFS_ISIZE(ip);
}
+ break;
}
if (bmv->bmv_length == -1) {
@@ -520,7 +618,8 @@ xfs_getbmap(
return -ENOMEM;
xfs_ilock(ip, XFS_IOLOCK_SHARED);
- if (whichfork == XFS_DATA_FORK) {
+ switch (whichfork) {
+ case XFS_DATA_FORK:
if (!(iflags & BMV_IF_DELALLOC) &&
(ip->i_delayed_blks || XFS_ISIZE(ip) > ip->i_d.di_size)) {
error = filemap_write_and_wait(VFS_I(ip)->i_mapping);
@@ -538,8 +637,14 @@ xfs_getbmap(
}
lock = xfs_ilock_data_map_shared(ip);
- } else {
+ break;
+ case XFS_COW_FORK:
+ lock = XFS_ILOCK_SHARED;
+ xfs_ilock(ip, lock);
+ break;
+ case XFS_ATTR_FORK:
lock = xfs_ilock_attr_map_shared(ip);
+ break;
}
/*
@@ -581,7 +686,8 @@ xfs_getbmap(
goto out_free_map;
ASSERT(nmap <= subnex);
- for (i = 0; i < nmap && nexleft && bmv->bmv_length; i++) {
+ for (i = 0; i < nmap && nexleft && bmv->bmv_length &&
+ cur_ext < bmv->bmv_count; i++) {
out[cur_ext].bmv_oflags = 0;
if (map[i].br_state == XFS_EXT_UNWRITTEN)
out[cur_ext].bmv_oflags |= BMV_OF_PREALLOC;
@@ -614,9 +720,16 @@ xfs_getbmap(
goto out_free_map;
}
- if (!xfs_getbmapx_fix_eof_hole(ip, &out[cur_ext],
- prealloced, bmvend,
- map[i].br_startblock))
+ /* Is this a shared block? */
+ error = xfs_getbmap_adjust_shared(ip, whichfork,
+ &map[i], &out[cur_ext], &inject_map);
+ if (error)
+ goto out_free_map;
+
+ if (!xfs_getbmapx_fix_eof_hole(ip, whichfork,
+ &out[cur_ext], prealloced, bmvend,
+ map[i].br_startblock,
+ inject_map.br_blockcount != 0))
goto out_free_map;
bmv->bmv_offset =
@@ -636,11 +749,16 @@ xfs_getbmap(
continue;
}
- nexleft--;
+ if (inject_map.br_blockcount) {
+ map[i] = inject_map;
+ i--;
+ } else
+ nexleft--;
bmv->bmv_entries++;
cur_ext++;
}
- } while (nmap && nexleft && bmv->bmv_length);
+ } while (nmap && nexleft && bmv->bmv_length &&
+ cur_ext < bmv->bmv_count);
out_free_map:
kmem_free(map);
--
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