diff options
| -rw-r--r-- | fs/gfs2/bmap.c | 210 |
1 files changed, 153 insertions, 57 deletions
diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c index fcf2f7d166de..69f846418ad5 100644 --- a/fs/gfs2/bmap.c +++ b/fs/gfs2/bmap.c @@ -278,6 +278,21 @@ static inline __be64 *metapointer(unsigned int height, const struct metapath *mp return p + mp->mp_list[height]; } +static inline const __be64 *metaend(unsigned int height, const struct metapath *mp) +{ + const struct buffer_head *bh = mp->mp_bh[height]; + return (const __be64 *)(bh->b_data + bh->b_size); +} + +static void clone_metapath(struct metapath *clone, struct metapath *mp) +{ + unsigned int hgt; + + *clone = *mp; + for (hgt = 0; hgt < mp->mp_aheight; hgt++) + get_bh(clone->mp_bh[hgt]); +} + static void gfs2_metapath_ra(struct gfs2_glock *gl, __be64 *start, __be64 *end) { const __be64 *t; @@ -419,6 +434,142 @@ static inline unsigned int gfs2_extent_length(void *start, unsigned int len, __b return (ptr - first); } +typedef const __be64 *(*gfs2_metadata_walker)( + struct metapath *mp, + const __be64 *start, const __be64 *end, + u64 factor, void *data); + +#define WALK_STOP ((__be64 *)0) +#define WALK_NEXT ((__be64 *)1) + +static int gfs2_walk_metadata(struct inode *inode, sector_t lblock, + u64 len, struct metapath *mp, gfs2_metadata_walker walker, + void *data) +{ + 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; + + for (hgt = ip->i_height - 1; hgt >= mp->mp_aheight; hgt--) + factor *= sdp->sd_inptrs; + + for (;;) { + u64 step; + + /* 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) + break; + if (step >= len) + break; + len -= step; + if (ptr != WALK_NEXT) { + BUG_ON(!*ptr); + mp->mp_list[hgt] += ptr - start; + 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; + if (!hgt) + break; + hgt--; + factor *= sdp->sd_inptrs; + + /* 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 (!hgt) + break; + goto 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; + hgt += ret; + for (; ret; ret--) + do_div(factor, sdp->sd_inptrs); + mp->mp_aheight = hgt + 1; + } + if (mp == &clone) + release_metapath(mp); + return ret; +} + +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) +{ + struct gfs2_hole_walker_args *args = data; + const __be64 *ptr; + + for (ptr = start; ptr < end; ptr++) { + if (*ptr) { + args->blocks += (ptr - start) * factor; + if (mp->mp_aheight == mp->mp_fheight) + return WALK_STOP; + return ptr; /* increase height */ + } + } + args->blocks += (end - start) * factor; + return WALK_NEXT; +} + +/** + * gfs2_hole_size - figure out the size of a hole + * @inode: The inode + * @lblock: The logical starting block number + * @len: How far to look (in blocks) + * @mp: The metapath at lblock + * @iomap: The iomap to store the hole size in + * + * This function modifies @mp. + * + * Returns: errno on error + */ +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; + + ret = gfs2_walk_metadata(inode, lblock, len, mp, gfs2_hole_walker, &args); + if (!ret) + iomap->length = args.blocks << inode->i_blkbits; + return ret; +} + static inline void bmap_lock(struct gfs2_inode *ip, int create) { if (create) @@ -615,62 +766,6 @@ static int gfs2_iomap_alloc(struct inode *inode, struct iomap *iomap, return 0; } -/** - * hole_size - figure out the size of a hole - * @inode: The inode - * @lblock: The logical starting block number - * @mp: The metapath - * - * Returns: The hole size in bytes - * - */ -static u64 hole_size(struct inode *inode, sector_t lblock, struct metapath *mp) -{ - struct gfs2_inode *ip = GFS2_I(inode); - struct gfs2_sbd *sdp = GFS2_SB(inode); - struct metapath mp_eof; - u64 factor = 1; - int hgt; - u64 holesz = 0; - const __be64 *first, *end, *ptr; - const struct buffer_head *bh; - u64 lblock_stop = (i_size_read(inode) - 1) >> inode->i_blkbits; - int zeroptrs; - bool done = false; - - /* Get another metapath, to the very last byte */ - find_metapath(sdp, lblock_stop, &mp_eof, ip->i_height); - for (hgt = ip->i_height - 1; hgt >= 0 && !done; hgt--) { - bh = mp->mp_bh[hgt]; - if (bh) { - zeroptrs = 0; - first = metapointer(hgt, mp); - end = (const __be64 *)(bh->b_data + bh->b_size); - - for (ptr = first; ptr < end; ptr++) { - if (*ptr) { - done = true; - break; - } else { - zeroptrs++; - } - } - } else { - zeroptrs = sdp->sd_inptrs; - } - if (factor * zeroptrs >= lblock_stop - lblock + 1) { - holesz = lblock_stop - lblock + 1; - break; - } - holesz += factor * zeroptrs; - - factor *= sdp->sd_inptrs; - if (hgt && (mp->mp_list[hgt - 1] < mp_eof.mp_list[hgt - 1])) - (mp->mp_list[hgt - 1])++; - } - return holesz << inode->i_blkbits; -} - static void gfs2_stuffed_iomap(struct inode *inode, struct iomap *iomap) { struct gfs2_inode *ip = GFS2_I(inode); @@ -726,6 +821,7 @@ int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length, lblock = pos >> inode->i_blkbits; lend = (pos + length + sdp->sd_sb.sb_bsize - 1) >> inode->i_blkbits; + len = lend - lblock; iomap->offset = lblock << inode->i_blkbits; iomap->addr = IOMAP_NULL_ADDR; @@ -780,7 +876,7 @@ do_alloc: if (pos >= size) ret = -ENOENT; else if (height <= ip->i_height) - iomap->length = hole_size(inode, lblock, &mp); + ret = gfs2_hole_size(inode, lblock, len, &mp, iomap); else iomap->length = size - pos; } |