[PATCH 1/2 v2] convert xfs_getbmap to take formatter functions

Eric Sandeen
2008-10-25T13:33:21Z

Preliminary work to hook up fiemap, this allows us to pass in an
arbitrary formatter to copy extent data back to userspace.

The formatter takes info for 1 extent, a pointer to the user "thing*"
and a pointer to a "filled" variable to indicate whether a userspace
buffer did get filled in (for fiemap, hole "extents" are skipped).

I'm just using the getbmapx struct as a "common denominator" because
as far as I can see, it holds all info that any formatters will care
about.

("*thing" because fiemap doesn't pass the user pointer around, but rather
has a pointer to a fiemap info structure, and helpers associated with it)

Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
---

Index: linux-2.6-xfs/fs/xfs/xfs_bmap.c
===================================================================
--- linux-2.6-xfs.orig/fs/xfs/xfs_bmap.c
+++ linux-2.6-xfs/fs/xfs/xfs_bmap.c
@@ -5805,9 +5805,9 @@ error0:
STATIC int
xfs_getbmapx_fix_eof_hole(
xfs_inode_t *ip, /* xfs incore inode pointer */
- struct getbmap *out, /* output structure */
+ struct getbmapx *out, /* output structure */
int prealloced, /* this is a file with
- * preallocated data space */
+ * preallocated data space */
__int64_t end, /* last block requested */
xfs_fsblock_t startblock)
{
@@ -5832,15 +5832,38 @@ xfs_getbmapx_fix_eof_hole(
return 1;
}

+int xfs_getbmapx_format(void __user **ap, struct getbmapx *bmv, int *filled)
+{
+ *filled = 0;
+ if (copy_to_user(*ap, bmv, sizeof(struct getbmapx)))
+ return XFS_ERROR(EFAULT);
+
+ *ap += sizeof(struct getbmapx);
+ *filled = 1;
+ return 0;
+}
+
+int xfs_getbmap_format(void __user **ap, struct getbmapx *bmv, int *filled)
+{
+ *filled = 0;
+ /* copy only getbmap portion (not getbmapx) */
+ if (copy_to_user(*ap, bmv, sizeof(struct getbmap)))
+ return XFS_ERROR(EFAULT);
+
+ *ap += sizeof(struct getbmap);
+ *filled = 1;
+ return 0;
+}
+
/*
- * Fcntl interface to xfs_bmapi.
+ * Get inode's extents as described in bmv, and format for output.
*/
int /* error code */
xfs_getbmap(
xfs_inode_t *ip,
- struct getbmap *bmv, /* user bmap structure */
- void __user *ap, /* pointer to user's array */
- int interface) /* interface flags */
+ struct getbmapx *bmv, /* user bmap structure */
+ xfs_bmap_format_t formatter, /* format to user */
+ void *arg) /* formatter arg */
{
__int64_t bmvend; /* last block requested */
int error; /* return value */
@@ -5853,19 +5876,20 @@ xfs_getbmap(
int nexleft; /* # of user extents left */
int subnex; /* # of bmapi's can do */
int nmap; /* number of map entries */
- struct getbmap out; /* output structure */
+ struct getbmapx out; /* output structure */
int whichfork; /* data or attr fork */
int prealloced; /* this is a file with
* preallocated data space */
int sh_unwritten; /* true, if unwritten */
/* extents listed separately */
+ int iflags; /* interface flags */
int bmapi_flags; /* flags for xfs_bmapi */
- __int32_t oflags; /* getbmapx bmv_oflags field */

mp = ip->i_mount;
+ iflags = bmv->bmv_iflags;

- whichfork = interface & BMV_IF_ATTRFORK ? XFS_ATTR_FORK : XFS_DATA_FORK;
- sh_unwritten = (interface & BMV_IF_PREALLOC) != 0;
+ whichfork = iflags & BMV_IF_ATTRFORK ? XFS_ATTR_FORK : XFS_DATA_FORK;
+ sh_unwritten = (iflags & BMV_IF_PREALLOC) != 0;

/* If the BMV_IF_NO_DMAPI_READ interface bit specified, do not
* generate a DMAPI read event. Otherwise, if the DM_EVENT_READ
@@ -5880,7 +5904,7 @@ xfs_getbmap(
* could misinterpret holes in a DMAPI file as true holes,
* when in fact they may represent offline user data.
*/
- if ((interface & BMV_IF_NO_DMAPI_READ) == 0 &&
+ if ((iflags & BMV_IF_NO_DMAPI_READ) == 0 &&
DM_EVENT_ENABLED(ip, DM_EVENT_READ) &&
whichfork == XFS_DATA_FORK) {
error = XFS_SEND_DATA(mp, DM_EVENT_READ, ip, 0, 0, 0, NULL);
@@ -5987,52 +6011,35 @@ xfs_getbmap(
ASSERT(nmap <= subnex);

for (i = 0; i < nmap && nexleft && bmv->bmv_length; i++) {
- nexleft--;
- oflags = (map[i].br_state == XFS_EXT_UNWRITTEN) ?
+ out.bmv_oflags = (map[i].br_state == XFS_EXT_UNWRITTEN) ?
BMV_OF_PREALLOC : 0;
out.bmv_offset = XFS_FSB_TO_BB(mp, map[i].br_startoff);
out.bmv_length = XFS_FSB_TO_BB(mp, map[i].br_blockcount);
+ out.bmv_unused1 = out.bmv_unused2 = 0;
ASSERT(map[i].br_startblock != DELAYSTARTBLOCK);
if (map[i].br_startblock == HOLESTARTBLOCK &&
whichfork == XFS_ATTR_FORK) {
/* came to the end of attribute fork */
goto unlock_and_return;
} else {
+ int filled; /* nr extents filled */
+
if (!xfs_getbmapx_fix_eof_hole(ip, &out,
prealloced, bmvend,
map[i].br_startblock)) {
goto unlock_and_return;
}

- /* return either getbmap/getbmapx structure. */
- if (interface & BMV_IF_EXTENDED) {
- struct getbmapx outx;
-
- GETBMAP_CONVERT(out,outx);
- outx.bmv_oflags = oflags;
- outx.bmv_unused1 = outx.bmv_unused2 = 0;
- if (copy_to_user(ap, &outx,
- sizeof(outx))) {
- error = XFS_ERROR(EFAULT);
- goto unlock_and_return;
- }
- } else {
- if (copy_to_user(ap, &out,
- sizeof(out))) {
- error = XFS_ERROR(EFAULT);
- goto unlock_and_return;
- }
- }
+ /* format results & advance arg */
+ error = formatter(&arg, &out, &filled);
+ if (error)
+ goto unlock_and_return;
+ nexleft -= filled;
bmv->bmv_offset =
out.bmv_offset + out.bmv_length;
bmv->bmv_length = MAX((__int64_t)0,
(__int64_t)(bmvend - bmv->bmv_offset));
bmv->bmv_entries++;
- ap = (interface & BMV_IF_EXTENDED) ?
- (void __user *)
- ((struct getbmapx __user *)ap + 1) :
- (void __user *)
- ((struct getbmap __user *)ap + 1);
}
}
} while (nmap && nexleft && bmv->bmv_length);
Index: linux-2.6-xfs/fs/xfs/xfs_bmap.h
===================================================================
--- linux-2.6-xfs.orig/fs/xfs/xfs_bmap.h
+++ linux-2.6-xfs/fs/xfs/xfs_bmap.h
@@ -356,15 +356,20 @@ xfs_bmap_finish(
xfs_bmap_free_t *flist, /* i/o: list extents to free */
int *committed); /* xact committed or not */

+/* bmap to userspace formatters - copy to user & advance pointer */
+typedef int (*xfs_bmap_format_t)(void __user **, struct getbmapx *, int *);
+int xfs_getbmapx_format(void __user **ap, struct getbmapx *bmv, int *filled);
+int xfs_getbmap_format(void __user **ap, struct getbmapx *bmv, int *filled);
+
/*
- * Fcntl interface to xfs_bmapi.
+ * Get inode's extents as described in bmv, and format for output.
*/
int /* error code */
xfs_getbmap(
xfs_inode_t *ip,
- struct getbmap *bmv, /* user bmap structure */
- void __user *ap, /* pointer to user's array */
- int iflags); /* interface flags */
+ struct getbmapx *bmv, /* user bmap structure */
+ xfs_bmap_format_t formatter, /* format to user */
+ void *arg); /* formatter arg */

/*
* Check if the endoff is outside the last extent. If so the caller will grow
Index: linux-2.6-xfs/fs/xfs/linux-2.6/xfs_ioctl.c
===================================================================
--- linux-2.6-xfs.orig/fs/xfs/linux-2.6/xfs_ioctl.c
+++ linux-2.6-xfs/fs/xfs/linux-2.6/xfs_ioctl.c
@@ -1262,25 +1262,26 @@ xfs_ioc_getbmap(
unsigned int cmd,
void __user *arg)
{
- struct getbmap bm;
- int iflags;
+ struct getbmapx bmx;
int error;

- if (copy_from_user(&bm, arg, sizeof(bm)))
+ if (copy_from_user(&bmx, arg, sizeof(struct getbmapx)))
return -XFS_ERROR(EFAULT);

- if (bm.bmv_count < 2)
+ if (bmx.bmv_count < 2)
return -XFS_ERROR(EINVAL);

- iflags = (cmd == XFS_IOC_GETBMAPA ? BMV_IF_ATTRFORK : 0);
+ bmx.bmv_iflags = (cmd == XFS_IOC_GETBMAPA ? BMV_IF_ATTRFORK : 0);
if (ioflags & IO_INVIS)
- iflags |= BMV_IF_NO_DMAPI_READ;
+ bmx.bmv_iflags |= BMV_IF_NO_DMAPI_READ;

- error = xfs_getbmap(ip, &bm, (struct getbmap __user *)arg+1, iflags);
+ error = xfs_getbmap(ip, &bmx, xfs_getbmap_format,
+ (struct getbmap __user *)arg+1);
if (error)
return -error;

- if (copy_to_user(arg, &bm, sizeof(bm)))
+ /* copy back header - only size of getbmap */
+ if (copy_to_user(arg, &bmx, sizeof(struct getbmap)))
return -XFS_ERROR(EFAULT);
return 0;
}
@@ -1291,8 +1292,6 @@ xfs_ioc_getbmapx(
void __user *arg)
{
struct getbmapx bmx;
- struct getbmap bm;
- int iflags;
int error;

if (copy_from_user(&bmx, arg, sizeof(bmx)))
@@ -1301,26 +1300,16 @@ xfs_ioc_getbmapx(
if (bmx.bmv_count < 2)
return -XFS_ERROR(EINVAL);

- /*
- * Map input getbmapx structure to a getbmap
- * structure for xfs_getbmap.
- */
- GETBMAP_CONVERT(bmx, bm);
-
- iflags = bmx.bmv_iflags;
-
- if (iflags & (~BMV_IF_VALID))
+ if (bmx.bmv_iflags & (~BMV_IF_VALID))
return -XFS_ERROR(EINVAL);

- iflags |= BMV_IF_EXTENDED;
-
- error = xfs_getbmap(ip, &bm, (struct getbmapx __user *)arg+1, iflags);
+ error = xfs_getbmap(ip, &bmx, xfs_getbmapx_format,
+ (struct getbmapx __user *)arg+1);
if (error)
return -error;

- GETBMAP_CONVERT(bm, bmx);
-
- if (copy_to_user(arg, &bmx, sizeof(bmx)))
+ /* copy back header */
+ if (copy_to_user(arg, &bmx, sizeof(struct getbmapx)))
return -XFS_ERROR(EFAULT);

return 0;
Index: linux-2.6-xfs/fs/xfs/xfs_fs.h
===================================================================
--- linux-2.6-xfs.orig/fs/xfs/xfs_fs.h
+++ linux-2.6-xfs/fs/xfs/xfs_fs.h
@@ -114,22 +114,10 @@ struct getbmapx {
#define BMV_IF_NO_DMAPI_READ 0x2 /* Do not generate DMAPI read event */
#define BMV_IF_PREALLOC 0x4 /* rtn status BMV_OF_PREALLOC if req */
#define BMV_IF_VALID (BMV_IF_ATTRFORK|BMV_IF_NO_DMAPI_READ|BMV_IF_PREALLOC)
-#ifdef __KERNEL__
-#define BMV_IF_EXTENDED 0x40000000 /* getpmapx if set */
-#endif

/* bmv_oflags values - returned for for each non-header segment */
#define BMV_OF_PREALLOC 0x1 /* segment = unwritten pre-allocation */

-/* Convert getbmap <-> getbmapx - move fields from p1 to p2. */
-#define GETBMAP_CONVERT(p1,p2) { \
- p2.bmv_offset = p1.bmv_offset; \
- p2.bmv_block = p1.bmv_block; \
- p2.bmv_length = p1.bmv_length; \
- p2.bmv_count = p1.bmv_count; \
- p2.bmv_entries = p1.bmv_entries; }
-
-
/*
* Structure for XFS_IOC_FSSETDM.
* For use by backup and restore programs to set the XFS on-disk inode