gfs2: gfs2_walk_metadata fix
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
parent
e21a712a96
commit
a27a0c9b6a
164
fs/gfs2/bmap.c
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)
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return mp->mp_aheight - x - 1;
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}
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static sector_t metapath_to_block(struct gfs2_sbd *sdp, struct metapath *mp)
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{
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sector_t factor = 1, block = 0;
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int hgt;
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for (hgt = mp->mp_fheight - 1; hgt >= 0; hgt--) {
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if (hgt < mp->mp_aheight)
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block += mp->mp_list[hgt] * factor;
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factor *= sdp->sd_inptrs;
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}
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return block;
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}
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static void release_metapath(struct metapath *mp)
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{
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int i;
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@ -430,60 +443,84 @@ static inline unsigned int gfs2_extent_length(struct buffer_head *bh, __be64 *pt
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return ptr - first;
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}
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typedef const __be64 *(*gfs2_metadata_walker)(
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struct metapath *mp,
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const __be64 *start, const __be64 *end,
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u64 factor, void *data);
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enum walker_status { WALK_STOP, WALK_FOLLOW, WALK_CONTINUE };
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#define WALK_STOP ((__be64 *)0)
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#define WALK_NEXT ((__be64 *)1)
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/*
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* gfs2_metadata_walker - walk an indirect block
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* @mp: Metapath to indirect block
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* @ptrs: Number of pointers to look at
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*
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* When returning WALK_FOLLOW, the walker must update @mp to point at the right
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* indirect block to follow.
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*/
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typedef enum walker_status (*gfs2_metadata_walker)(struct metapath *mp,
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unsigned int ptrs);
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static int gfs2_walk_metadata(struct inode *inode, sector_t lblock,
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u64 len, struct metapath *mp, gfs2_metadata_walker walker,
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void *data)
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/*
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* gfs2_walk_metadata - walk a tree of indirect blocks
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* @inode: The inode
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* @mp: Starting point of walk
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* @max_len: Maximum number of blocks to walk
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* @walker: Called during the walk
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*
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* Returns 1 if the walk was stopped by @walker, 0 if we went past @max_len or
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* past the end of metadata, and a negative error code otherwise.
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*/
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static int gfs2_walk_metadata(struct inode *inode, struct metapath *mp,
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u64 max_len, gfs2_metadata_walker walker)
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{
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struct metapath clone;
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struct gfs2_inode *ip = GFS2_I(inode);
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struct gfs2_sbd *sdp = GFS2_SB(inode);
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const __be64 *start, *end, *ptr;
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u64 factor = 1;
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unsigned int hgt;
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int ret = 0;
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int ret;
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for (hgt = ip->i_height - 1; hgt >= mp->mp_aheight; hgt--)
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/*
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* The walk starts in the lowest allocated indirect block, which may be
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* before the position indicated by @mp. Adjust @max_len accordingly
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* to avoid a short walk.
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*/
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for (hgt = mp->mp_fheight - 1; hgt >= mp->mp_aheight; hgt--) {
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max_len += mp->mp_list[hgt] * factor;
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mp->mp_list[hgt] = 0;
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factor *= sdp->sd_inptrs;
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}
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for (;;) {
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u64 step;
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u16 start = mp->mp_list[hgt];
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enum walker_status status;
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unsigned int ptrs;
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u64 len;
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/* Walk indirect block. */
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start = metapointer(hgt, mp);
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end = metaend(hgt, mp);
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step = (end - start) * factor;
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if (step > len)
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end = start + DIV_ROUND_UP_ULL(len, factor);
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ptr = walker(mp, start, end, factor, data);
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if (ptr == WALK_STOP)
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ptrs = (hgt >= 1 ? sdp->sd_inptrs : sdp->sd_diptrs) - start;
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len = ptrs * factor;
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if (len > max_len)
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ptrs = DIV_ROUND_UP_ULL(max_len, factor);
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status = walker(mp, ptrs);
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switch (status) {
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case WALK_STOP:
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return 1;
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case WALK_FOLLOW:
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BUG_ON(mp->mp_aheight == mp->mp_fheight);
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ptrs = mp->mp_list[hgt] - start;
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len = ptrs * factor;
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break;
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if (step >= len)
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case WALK_CONTINUE:
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break;
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len -= step;
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if (ptr != WALK_NEXT) {
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BUG_ON(!*ptr);
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mp->mp_list[hgt] += ptr - start;
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goto fill_up_metapath;
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}
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if (len >= max_len)
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break;
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max_len -= len;
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if (status == WALK_FOLLOW)
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goto fill_up_metapath;
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lower_metapath:
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/* Decrease height of metapath. */
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if (mp != &clone) {
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clone_metapath(&clone, mp);
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mp = &clone;
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}
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brelse(mp->mp_bh[hgt]);
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mp->mp_bh[hgt] = NULL;
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mp->mp_list[hgt] = 0;
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if (!hgt)
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break;
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hgt--;
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@ -491,10 +528,7 @@ lower_metapath:
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/* Advance in metadata tree. */
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(mp->mp_list[hgt])++;
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start = metapointer(hgt, mp);
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end = metaend(hgt, mp);
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if (start >= end) {
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mp->mp_list[hgt] = 0;
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if (mp->mp_list[hgt] >= sdp->sd_inptrs) {
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if (!hgt)
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break;
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goto lower_metapath;
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@ -502,44 +536,36 @@ lower_metapath:
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fill_up_metapath:
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/* Increase height of metapath. */
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if (mp != &clone) {
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clone_metapath(&clone, mp);
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mp = &clone;
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}
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ret = fillup_metapath(ip, mp, ip->i_height - 1);
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if (ret < 0)
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break;
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return ret;
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hgt += ret;
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for (; ret; ret--)
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do_div(factor, sdp->sd_inptrs);
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mp->mp_aheight = hgt + 1;
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}
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if (mp == &clone)
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release_metapath(mp);
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return ret;
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return 0;
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}
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struct gfs2_hole_walker_args {
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u64 blocks;
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};
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static const __be64 *gfs2_hole_walker(struct metapath *mp,
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const __be64 *start, const __be64 *end,
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u64 factor, void *data)
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static enum walker_status gfs2_hole_walker(struct metapath *mp,
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unsigned int ptrs)
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{
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struct gfs2_hole_walker_args *args = data;
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const __be64 *ptr;
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const __be64 *start, *ptr, *end;
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unsigned int hgt;
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hgt = mp->mp_aheight - 1;
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start = metapointer(hgt, mp);
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end = start + ptrs;
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for (ptr = start; ptr < end; ptr++) {
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if (*ptr) {
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args->blocks += (ptr - start) * factor;
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mp->mp_list[hgt] += ptr - start;
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if (mp->mp_aheight == mp->mp_fheight)
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return WALK_STOP;
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return ptr; /* increase height */
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return WALK_FOLLOW;
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}
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}
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args->blocks += (end - start) * factor;
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return WALK_NEXT;
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return WALK_CONTINUE;
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}
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/**
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@ -557,12 +583,24 @@ static const __be64 *gfs2_hole_walker(struct metapath *mp,
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static int gfs2_hole_size(struct inode *inode, sector_t lblock, u64 len,
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struct metapath *mp, struct iomap *iomap)
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{
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struct gfs2_hole_walker_args args = { };
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int ret = 0;
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struct metapath clone;
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u64 hole_size;
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int ret;
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ret = gfs2_walk_metadata(inode, lblock, len, mp, gfs2_hole_walker, &args);
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if (!ret)
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iomap->length = args.blocks << inode->i_blkbits;
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clone_metapath(&clone, mp);
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ret = gfs2_walk_metadata(inode, &clone, len, gfs2_hole_walker);
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if (ret < 0)
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goto out;
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if (ret == 1)
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hole_size = metapath_to_block(GFS2_SB(inode), &clone) - lblock;
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else
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hole_size = len;
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iomap->length = hole_size << inode->i_blkbits;
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ret = 0;
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out:
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release_metapath(&clone);
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return ret;
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}
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