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GFS2: Implement iomap for block_map
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This patch implements iomap for block mapping, and switches the
block_map function to use it under the covers.

The additional IOMAP_F_BOUNDARY iomap flag indicates when iomap has
reached a "metadata boundary" and fetching the next mapping is likely to
incur an additional I/O.  This flag is used for setting the bh buffer
boundary flag.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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Bob Peterson authored and Andreas Gruenbacher committed Oct 31, 2017
1 parent 5f8bd44 commit 3974320
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Showing 4 changed files with 276 additions and 69 deletions.
273 changes: 205 additions & 68 deletions fs/gfs2/bmap.c
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@
#include <linux/blkdev.h>
#include <linux/gfs2_ondisk.h>
#include <linux/crc32.h>
#include <linux/iomap.h>

#include "gfs2.h"
#include "incore.h"
Expand Down Expand Up @@ -505,47 +506,46 @@ static inline unsigned int hptrs(struct gfs2_sbd *sdp, const unsigned int hgt)
* Returns: errno on error
*/

static int gfs2_bmap_alloc(struct inode *inode, const sector_t lblock,
bool zero_new, struct metapath *mp,
const size_t maxlen, sector_t *dblock,
unsigned *dblks)
static int gfs2_iomap_alloc(struct inode *inode, struct iomap *iomap,
unsigned flags, struct metapath *mp)
{
struct gfs2_inode *ip = GFS2_I(inode);
struct gfs2_sbd *sdp = GFS2_SB(inode);
struct super_block *sb = sdp->sd_vfs;
struct buffer_head *dibh = mp->mp_bh[0];
u64 bn;
unsigned n, i, blks, alloced = 0, iblks = 0, branch_start = 0;
unsigned dblks = 0;
unsigned ptrs_per_blk;
const unsigned end_of_metadata = mp->mp_fheight - 1;
int ret;
int eob = 0;
enum alloc_state state;
__be64 *ptr;
__be64 zero_bn = 0;
size_t maxlen = iomap->length >> inode->i_blkbits;

BUG_ON(mp->mp_aheight < 1);
BUG_ON(dibh == NULL);

*dblock = 0;
*dblks = 0;
gfs2_trans_add_meta(ip->i_gl, dibh);

if (mp->mp_fheight == mp->mp_aheight) {
struct buffer_head *bh;
int eob;

/* Bottom indirect block exists, find unalloced extent size */
ptr = metapointer(end_of_metadata, mp);
bh = mp->mp_bh[end_of_metadata];
*dblks = gfs2_extent_length(bh->b_data, bh->b_size, ptr,
maxlen, &eob);
BUG_ON(*dblks < 1);
dblks = gfs2_extent_length(bh->b_data, bh->b_size, ptr,
maxlen, &eob);
BUG_ON(dblks < 1);
state = ALLOC_DATA;
} else {
/* Need to allocate indirect blocks */
ptrs_per_blk = mp->mp_fheight > 1 ? sdp->sd_inptrs :
sdp->sd_diptrs;
*dblks = min(maxlen, (size_t)(ptrs_per_blk -
mp->mp_list[end_of_metadata]));
dblks = min(maxlen, (size_t)(ptrs_per_blk -
mp->mp_list[end_of_metadata]));
if (mp->mp_fheight == ip->i_height) {
/* Writing into existing tree, extend tree down */
iblks = mp->mp_fheight - mp->mp_aheight;
Expand All @@ -561,7 +561,7 @@ static int gfs2_bmap_alloc(struct inode *inode, const sector_t lblock,

/* start of the second part of the function (state machine) */

blks = *dblks + iblks;
blks = dblks + iblks;
i = mp->mp_aheight;
do {
int error;
Expand Down Expand Up @@ -618,74 +618,153 @@ static int gfs2_bmap_alloc(struct inode *inode, const sector_t lblock,
break;
/* Tree complete, adding data blocks */
case ALLOC_DATA:
BUG_ON(n > *dblks);
BUG_ON(n > dblks);
BUG_ON(mp->mp_bh[end_of_metadata] == NULL);
gfs2_trans_add_meta(ip->i_gl, mp->mp_bh[end_of_metadata]);
*dblks = n;
dblks = n;
ptr = metapointer(end_of_metadata, mp);
*dblock = bn;
iomap->addr = bn << inode->i_blkbits;
iomap->flags |= IOMAP_F_NEW;
while (n-- > 0)
*ptr++ = cpu_to_be64(bn++);
if (zero_new) {
ret = sb_issue_zeroout(sb, *dblock, *dblks,
GFP_NOFS);
if (flags & IOMAP_ZERO) {
ret = sb_issue_zeroout(sb, iomap->addr >> inode->i_blkbits,
dblks, GFP_NOFS);
if (ret) {
fs_err(sdp,
"Failed to zero data buffers\n");
flags &= ~IOMAP_ZERO;
}
}
break;
}
} while ((state != ALLOC_DATA) || !(*dblock));
} while (iomap->addr == IOMAP_NULL_ADDR);

iomap->length = (u64)dblks << inode->i_blkbits;
ip->i_height = mp->mp_fheight;
gfs2_add_inode_blocks(&ip->i_inode, alloced);
gfs2_dinode_out(ip, mp->mp_bh[0]->b_data);
return 0;
}

/**
* gfs2_block_map - Map a block from an inode to a disk block
* hole_size - figure out the size of a hole
* @inode: The inode
* @lblock: The logical block number
* @bh_map: The bh to be mapped
* @create: True if its ok to alloc blocks to satify the request
* @lblock: The logical starting block number
* @mp: The metapath
*
* Sets buffer_mapped() if successful, sets buffer_boundary() if a
* read of metadata will be required before the next block can be
* mapped. Sets buffer_new() if new blocks were allocated.
* Returns: The hole size in bytes
*
* Returns: errno
*/
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;

int gfs2_block_map(struct inode *inode, sector_t lblock,
struct buffer_head *bh_map, int create)
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);

iomap->addr = (ip->i_no_addr << inode->i_blkbits) +
sizeof(struct gfs2_dinode);
iomap->offset = 0;
iomap->length = i_size_read(inode);
iomap->type = IOMAP_MAPPED;
iomap->flags = IOMAP_F_DATA_INLINE;
}

/**
* gfs2_iomap_begin - Map blocks from an inode to disk blocks
* @inode: The inode
* @pos: Starting position in bytes
* @length: Length to map, in bytes
* @flags: iomap flags
* @iomap: The iomap structure
*
* Returns: errno
*/
int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
unsigned flags, struct iomap *iomap)
{
struct gfs2_inode *ip = GFS2_I(inode);
struct gfs2_sbd *sdp = GFS2_SB(inode);
struct metapath mp = { .mp_aheight = 1, };
unsigned int factor = sdp->sd_sb.sb_bsize;
const size_t maxlen = bh_map->b_size >> inode->i_blkbits;
const u64 *arr = sdp->sd_heightsize;
__be64 *ptr;
u64 size;
struct metapath mp;
sector_t lblock;
sector_t lend;
int ret;
int eob;
unsigned int len;
struct buffer_head *bh;
u8 height;
bool zero_new = false;
sector_t dblock = 0;
unsigned dblks;

BUG_ON(maxlen == 0);
trace_gfs2_iomap_start(ip, pos, length, flags);
if (!length) {
ret = -EINVAL;
goto out;
}

memset(&mp, 0, sizeof(mp));
bmap_lock(ip, create);
clear_buffer_mapped(bh_map);
clear_buffer_new(bh_map);
clear_buffer_boundary(bh_map);
trace_gfs2_bmap(ip, bh_map, lblock, create, 1);
if ((flags & IOMAP_REPORT) && gfs2_is_stuffed(ip)) {
gfs2_stuffed_iomap(inode, iomap);
if (pos >= iomap->length)
return -ENOENT;
ret = 0;
goto out;
}

lblock = pos >> inode->i_blkbits;
lend = (pos + length + sdp->sd_sb.sb_bsize - 1) >> inode->i_blkbits;

iomap->offset = lblock << inode->i_blkbits;
iomap->addr = IOMAP_NULL_ADDR;
iomap->type = IOMAP_HOLE;
iomap->length = (u64)(lend - lblock) << inode->i_blkbits;
iomap->flags = IOMAP_F_MERGED;
bmap_lock(ip, 0);

/*
* Directory data blocks have a struct gfs2_meta_header header, so the
Expand All @@ -699,56 +778,114 @@ int gfs2_block_map(struct inode *inode, sector_t lblock,

ret = gfs2_meta_inode_buffer(ip, &mp.mp_bh[0]);
if (ret)
goto out;
goto out_release;

height = ip->i_height;
size = (lblock + 1) * factor;
while (size > arr[height])
while ((lblock + 1) * factor > arr[height])
height++;
find_metapath(sdp, lblock, &mp, height);
mp.mp_aheight = 1;
if (height > ip->i_height || gfs2_is_stuffed(ip))
goto do_alloc;

ret = lookup_metapath(ip, &mp);
if (ret < 0)
goto out;
goto out_release;

if (mp.mp_aheight != ip->i_height)
goto do_alloc;

ptr = metapointer(ip->i_height - 1, &mp);
if (*ptr == 0)
goto do_alloc;
map_bh(bh_map, inode->i_sb, be64_to_cpu(*ptr));

iomap->type = IOMAP_MAPPED;
iomap->addr = be64_to_cpu(*ptr) << inode->i_blkbits;

bh = mp.mp_bh[ip->i_height - 1];
len = gfs2_extent_length(bh->b_data, bh->b_size, ptr, maxlen, &eob);
bh_map->b_size = (len << inode->i_blkbits);
len = gfs2_extent_length(bh->b_data, bh->b_size, ptr, lend - lblock, &eob);
if (eob)
set_buffer_boundary(bh_map);
iomap->flags |= IOMAP_F_BOUNDARY;
iomap->length = (u64)len << inode->i_blkbits;

ret = 0;
out:

out_release:
release_metapath(&mp);
trace_gfs2_bmap(ip, bh_map, lblock, create, ret);
bmap_unlock(ip, create);
bmap_unlock(ip, 0);
out:
trace_gfs2_iomap_end(ip, iomap, ret);
return ret;

do_alloc:
/* All allocations are done here, firstly check create flag */
if (!create) {
BUG_ON(gfs2_is_stuffed(ip));
if (!(flags & IOMAP_WRITE)) {
if (pos >= i_size_read(inode)) {
ret = -ENOENT;
goto out_release;
}
ret = 0;
goto out;
iomap->length = hole_size(inode, lblock, &mp);
goto out_release;
}

/* At this point ret is the tree depth of already allocated blocks */
ret = gfs2_iomap_alloc(inode, iomap, flags, &mp);
goto out_release;
}

/**
* gfs2_block_map - Map a block from an inode to a disk block
* @inode: The inode
* @lblock: The logical block number
* @bh_map: The bh to be mapped
* @create: True if its ok to alloc blocks to satify the request
*
* Sets buffer_mapped() if successful, sets buffer_boundary() if a
* read of metadata will be required before the next block can be
* mapped. Sets buffer_new() if new blocks were allocated.
*
* Returns: errno
*/

int gfs2_block_map(struct inode *inode, sector_t lblock,
struct buffer_head *bh_map, int create)
{
struct gfs2_inode *ip = GFS2_I(inode);
struct iomap iomap;
int ret, flags = 0;

clear_buffer_mapped(bh_map);
clear_buffer_new(bh_map);
clear_buffer_boundary(bh_map);
trace_gfs2_bmap(ip, bh_map, lblock, create, 1);

if (create)
flags |= IOMAP_WRITE;
if (buffer_zeronew(bh_map))
zero_new = true;
ret = gfs2_bmap_alloc(inode, lblock, zero_new, &mp, maxlen, &dblock,
&dblks);
if (ret == 0) {
map_bh(bh_map, inode->i_sb, dblock);
bh_map->b_size = dblks << inode->i_blkbits;
set_buffer_new(bh_map);
flags |= IOMAP_ZERO;
ret = gfs2_iomap_begin(inode, (loff_t)lblock << inode->i_blkbits,
bh_map->b_size, flags, &iomap);
if (ret) {
if (!create && ret == -ENOENT) {
/* Return unmapped buffer beyond the end of file. */
ret = 0;
}
goto out;
}

if (iomap.length > bh_map->b_size) {
iomap.length = bh_map->b_size;
iomap.flags &= ~IOMAP_F_BOUNDARY;
}
goto out;
if (iomap.addr != IOMAP_NULL_ADDR)
map_bh(bh_map, inode->i_sb, iomap.addr >> inode->i_blkbits);
bh_map->b_size = iomap.length;
if (iomap.flags & IOMAP_F_BOUNDARY)
set_buffer_boundary(bh_map);
if (iomap.flags & IOMAP_F_NEW)
set_buffer_new(bh_map);

out:
trace_gfs2_bmap(ip, bh_map, lblock, create, ret);
return ret;
}

/*
Expand Down
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