renegade-project/linux-next
2
0
Fork 0
mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-21 19:53:59 +08:00
Code

gfs2: gfs2_walk_metadata fix

Browse Source 
It turns out that the current version of gfs2_metadata_walker suffers
from multiple problems that can cause gfs2_hole_size to report an
incorrect size.  This will confuse fiemap as well as lseek with the
SEEK_DATA flag.

Fix that by changing gfs2_hole_walker to compute the metapath to the
first data block after the hole (if any), and compute the hole size
based on that.

Fixes xfstest generic/490.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Bob Peterson <rpeterso@redhat.com>
Cc: stable@vger.kernel.org # v4.18+
This commit is contained in:
Andreas Gruenbacher 2019-08-05 12:22:03 +01:00
parent e21a712a96
commit a27a0c9b6a
1 changed files with 101 additions and 63 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

164
fs/gfs2/bmap.c
View File

@ -390,6 +390,19 @@ static int fillup_metapath(struct gfs2_inode *ip, struct metapath *mp, int h)
return mp->mp_aheight - x - 1;
}
static sector_t metapath_to_block(struct gfs2_sbd *sdp, struct metapath *mp)
{
sector_t factor = 1, block = 0;
int hgt;
for (hgt = mp->mp_fheight - 1; hgt >= 0; hgt--) {
if (hgt < mp->mp_aheight)
block += mp->mp_list[hgt] * factor;
factor *= sdp->sd_inptrs;
}
return block;
}
static void release_metapath(struct metapath *mp)
{
int i;
@ -430,60 +443,84 @@ static inline unsigned int gfs2_extent_length(struct buffer_head *bh, __be64 *pt
return ptr - first;
}
typedef const __be64 *(*gfs2_metadata_walker)(
struct metapath *mp,
const __be64 *start, const __be64 *end,
u64 factor, void *data);
enum walker_status { WALK_STOP, WALK_FOLLOW, WALK_CONTINUE };
#define WALK_STOP ((__be64 *)0)
#define WALK_NEXT ((__be64 *)1)
/*
* gfs2_metadata_walker - walk an indirect block
* @mp: Metapath to indirect block
* @ptrs: Number of pointers to look at
*
* When returning WALK_FOLLOW, the walker must update @mp to point at the right
* indirect block to follow.
*/
typedef enum walker_status (*gfs2_metadata_walker)(struct metapath *mp,
unsigned int ptrs);
static int gfs2_walk_metadata(struct inode *inode, sector_t lblock,
u64 len, struct metapath *mp, gfs2_metadata_walker walker,
void *data)
/*
* gfs2_walk_metadata - walk a tree of indirect blocks
* @inode: The inode
* @mp: Starting point of walk
* @max_len: Maximum number of blocks to walk
* @walker: Called during the walk
*
* Returns 1 if the walk was stopped by @walker, 0 if we went past @max_len or
* past the end of metadata, and a negative error code otherwise.
*/
static int gfs2_walk_metadata(struct inode *inode, struct metapath *mp,
u64 max_len, gfs2_metadata_walker walker)
{
struct metapath clone;
struct gfs2_inode *ip = GFS2_I(inode);
struct gfs2_sbd *sdp = GFS2_SB(inode);
const __be64 *start, *end, *ptr;
u64 factor = 1;
unsigned int hgt;
int ret = 0;
int ret;
for (hgt = ip->i_height - 1; hgt >= mp->mp_aheight; hgt--)
/*
* The walk starts in the lowest allocated indirect block, which may be
* before the position indicated by @mp. Adjust @max_len accordingly
* to avoid a short walk.
*/
for (hgt = mp->mp_fheight - 1; hgt >= mp->mp_aheight; hgt--) {
max_len += mp->mp_list[hgt] * factor;
mp->mp_list[hgt] = 0;
factor *= sdp->sd_inptrs;
}
for (;;) {
u64 step;
u16 start = mp->mp_list[hgt];
enum walker_status status;
unsigned int ptrs;
u64 len;
/* Walk indirect block. */
start = metapointer(hgt, mp);
end = metaend(hgt, mp);
step = (end - start) * factor;
if (step > len)
end = start + DIV_ROUND_UP_ULL(len, factor);
ptr = walker(mp, start, end, factor, data);
if (ptr == WALK_STOP)
ptrs = (hgt >= 1 ? sdp->sd_inptrs : sdp->sd_diptrs) - start;
len = ptrs * factor;
if (len > max_len)
ptrs = DIV_ROUND_UP_ULL(max_len, factor);
status = walker(mp, ptrs);
switch (status) {
case WALK_STOP:
return 1;
case WALK_FOLLOW:
BUG_ON(mp->mp_aheight == mp->mp_fheight);
ptrs = mp->mp_list[hgt] - start;
len = ptrs * factor;
break;
if (step >= len)
case WALK_CONTINUE:
break;
len -= step;
if (ptr != WALK_NEXT) {
BUG_ON(!*ptr);
mp->mp_list[hgt] += ptr - start;
goto fill_up_metapath;
}
if (len >= max_len)
break;
max_len -= len;
if (status == WALK_FOLLOW)
goto fill_up_metapath;
lower_metapath:
/* Decrease height of metapath. */
if (mp != &clone) {
clone_metapath(&clone, mp);
mp = &clone;
}
brelse(mp->mp_bh[hgt]);
mp->mp_bh[hgt] = NULL;
mp->mp_list[hgt] = 0;
if (!hgt)
break;
hgt--;
@ -491,10 +528,7 @@ lower_metapath:
/* Advance in metadata tree. */
(mp->mp_list[hgt])++;
start = metapointer(hgt, mp);
end = metaend(hgt, mp);
if (start >= end) {
mp->mp_list[hgt] = 0;
if (mp->mp_list[hgt] >= sdp->sd_inptrs) {
if (!hgt)
break;
goto lower_metapath;
@ -502,44 +536,36 @@ lower_metapath:
fill_up_metapath:
/* Increase height of metapath. */
if (mp != &clone) {
clone_metapath(&clone, mp);
mp = &clone;
}
ret = fillup_metapath(ip, mp, ip->i_height - 1);
if (ret < 0)
break;
return ret;
hgt += ret;
for (; ret; ret--)
do_div(factor, sdp->sd_inptrs);
mp->mp_aheight = hgt + 1;
}
if (mp == &clone)
release_metapath(mp);
return ret;
return 0;
}
struct gfs2_hole_walker_args {
u64 blocks;
};
static const __be64 *gfs2_hole_walker(struct metapath *mp,
const __be64 *start, const __be64 *end,
u64 factor, void *data)
static enum walker_status gfs2_hole_walker(struct metapath *mp,
unsigned int ptrs)
{
struct gfs2_hole_walker_args *args = data;
const __be64 *ptr;
const __be64 *start, *ptr, *end;
unsigned int hgt;
hgt = mp->mp_aheight - 1;
start = metapointer(hgt, mp);
end = start + ptrs;
for (ptr = start; ptr < end; ptr++) {
if (*ptr) {
args->blocks += (ptr - start) * factor;
mp->mp_list[hgt] += ptr - start;
if (mp->mp_aheight == mp->mp_fheight)
return WALK_STOP;
return ptr; /* increase height */
return WALK_FOLLOW;
}
}
args->blocks += (end - start) * factor;
return WALK_NEXT;
return WALK_CONTINUE;
}
/**
@ -557,12 +583,24 @@ static const __be64 *gfs2_hole_walker(struct metapath *mp,
static int gfs2_hole_size(struct inode *inode, sector_t lblock, u64 len,
struct metapath *mp, struct iomap *iomap)
{
struct gfs2_hole_walker_args args = { };
int ret = 0;
struct metapath clone;
u64 hole_size;
int ret;
ret = gfs2_walk_metadata(inode, lblock, len, mp, gfs2_hole_walker, &args);
if (!ret)
iomap->length = args.blocks << inode->i_blkbits;
clone_metapath(&clone, mp);
ret = gfs2_walk_metadata(inode, &clone, len, gfs2_hole_walker);
if (ret < 0)
goto out;
if (ret == 1)
hole_size = metapath_to_block(GFS2_SB(inode), &clone) - lblock;
else
hole_size = len;
iomap->length = hole_size << inode->i_blkbits;
ret = 0;
out:
release_metapath(&clone);
return ret;
}