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Fix incorrect lseek / fiemap results

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Merge tag 'gfs2-v5.3-rc3.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2

Pull gfs2 fix from Andreas Gruenbacher:
 "Fix incorrect lseek / fiemap results"

* tag 'gfs2-v5.3-rc3.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2:
  gfs2: gfs2_walk_metadata fix
This commit is contained in:
Linus Torvalds 2019-08-10 15:41:15 -07:00
commit 829890d266
1 changed files with 101 additions and 63 deletions
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164
fs/gfs2/bmap.c
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@ -390,6 +390,19 @@ static int fillup_metapath(struct gfs2_inode *ip, struct metapath *mp, int h)
return mp->mp_aheight - x - 1; 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) static void release_metapath(struct metapath *mp)
{ {
int i; int i;
@ -430,60 +443,84 @@ static inline unsigned int gfs2_extent_length(struct buffer_head *bh, __be64 *pt
return ptr - first; return ptr - first;
} }
typedef const __be64 *(*gfs2_metadata_walker)( enum walker_status { WALK_STOP, WALK_FOLLOW, WALK_CONTINUE };
struct metapath *mp,
const __be64 *start, const __be64 *end,
u64 factor, void *data);
#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, * gfs2_walk_metadata - walk a tree of indirect blocks
void *data) * @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_inode *ip = GFS2_I(inode);
struct gfs2_sbd *sdp = GFS2_SB(inode); struct gfs2_sbd *sdp = GFS2_SB(inode);
const __be64 *start, *end, *ptr;
u64 factor = 1; u64 factor = 1;
unsigned int hgt; 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; factor *= sdp->sd_inptrs;
}
for (;;) { for (;;) {
u64 step; u16 start = mp->mp_list[hgt];
enum walker_status status;
unsigned int ptrs;
u64 len;
/* Walk indirect block. */ /* Walk indirect block. */
start = metapointer(hgt, mp); ptrs = (hgt >= 1 ? sdp->sd_inptrs : sdp->sd_diptrs) - start;
end = metaend(hgt, mp); len = ptrs * factor;
if (len > max_len)
step = (end - start) * factor; ptrs = DIV_ROUND_UP_ULL(max_len, factor);
if (step > len) status = walker(mp, ptrs);
end = start + DIV_ROUND_UP_ULL(len, factor); switch (status) {
case WALK_STOP:
ptr = walker(mp, start, end, factor, data); return 1;
if (ptr == WALK_STOP) case WALK_FOLLOW:
BUG_ON(mp->mp_aheight == mp->mp_fheight);
ptrs = mp->mp_list[hgt] - start;
len = ptrs * factor;
break; break;
if (step >= len) case WALK_CONTINUE:
break; 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: lower_metapath:
/* Decrease height of metapath. */ /* Decrease height of metapath. */
if (mp != &clone) {
clone_metapath(&clone, mp);
mp = &clone;
}
brelse(mp->mp_bh[hgt]); brelse(mp->mp_bh[hgt]);
mp->mp_bh[hgt] = NULL; mp->mp_bh[hgt] = NULL;
mp->mp_list[hgt] = 0;
if (!hgt) if (!hgt)
break; break;
hgt--; hgt--;
@ -491,10 +528,7 @@ lower_metapath:
/* Advance in metadata tree. */ /* Advance in metadata tree. */
(mp->mp_list[hgt])++; (mp->mp_list[hgt])++;
start = metapointer(hgt, mp); if (mp->mp_list[hgt] >= sdp->sd_inptrs) {
end = metaend(hgt, mp);
if (start >= end) {
mp->mp_list[hgt] = 0;
if (!hgt) if (!hgt)
break; break;
goto lower_metapath; goto lower_metapath;
@ -502,44 +536,36 @@ lower_metapath:
fill_up_metapath: fill_up_metapath:
/* Increase height of metapath. */ /* Increase height of metapath. */
if (mp != &clone) {
clone_metapath(&clone, mp);
mp = &clone;
}
ret = fillup_metapath(ip, mp, ip->i_height - 1); ret = fillup_metapath(ip, mp, ip->i_height - 1);
if (ret < 0) if (ret < 0)
break; return ret;
hgt += ret; hgt += ret;
for (; ret; ret--) for (; ret; ret--)
do_div(factor, sdp->sd_inptrs); do_div(factor, sdp->sd_inptrs);
mp->mp_aheight = hgt + 1; mp->mp_aheight = hgt + 1;
} }
if (mp == &clone) return 0;
release_metapath(mp);
return ret;
} }
struct gfs2_hole_walker_args { static enum walker_status gfs2_hole_walker(struct metapath *mp,
u64 blocks; unsigned int ptrs)
};
static const __be64 *gfs2_hole_walker(struct metapath *mp,
const __be64 *start, const __be64 *end,
u64 factor, void *data)
{ {
struct gfs2_hole_walker_args *args = data; const __be64 *start, *ptr, *end;
const __be64 *ptr; unsigned int hgt;
hgt = mp->mp_aheight - 1;
start = metapointer(hgt, mp);
end = start + ptrs;
for (ptr = start; ptr < end; ptr++) { for (ptr = start; ptr < end; ptr++) {
if (*ptr) { if (*ptr) {
args->blocks += (ptr - start) * factor; mp->mp_list[hgt] += ptr - start;
if (mp->mp_aheight == mp->mp_fheight) if (mp->mp_aheight == mp->mp_fheight)
return WALK_STOP; return WALK_STOP;
return ptr; /* increase height */ return WALK_FOLLOW;
} }
} }
args->blocks += (end - start) * factor; return WALK_CONTINUE;
return WALK_NEXT;
} }
/** /**
@ -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, static int gfs2_hole_size(struct inode *inode, sector_t lblock, u64 len,
struct metapath *mp, struct iomap *iomap) struct metapath *mp, struct iomap *iomap)
{ {
struct gfs2_hole_walker_args args = { }; struct metapath clone;
int ret = 0; u64 hole_size;
int ret;
ret = gfs2_walk_metadata(inode, lblock, len, mp, gfs2_hole_walker, &args); clone_metapath(&clone, mp);
if (!ret) ret = gfs2_walk_metadata(inode, &clone, len, gfs2_hole_walker);
iomap->length = args.blocks << inode->i_blkbits; 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; return ret;
} }