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linux/fs/gfs2/bmap.c
Steven Whitehouse ce276b06e8 [GFS2] Reduce inode size by merging fields 
There were three fields being used to keep track of the location
of the most recently allocated block for each inode. These have
been merged into a single field in order to better keep the
data and metadata for an inode close on disk, and also to reduce
the space required for storage.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2008-03-31 10:40:37 +01:00

1227 lines
29 KiB
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/*
* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
* Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
* of the GNU General Public License version 2.
*/
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
#include <linux/gfs2_ondisk.h>
#include <linux/crc32.h>
#include <linux/lm_interface.h>
#include "gfs2.h"
#include "incore.h"
#include "bmap.h"
#include "glock.h"
#include "inode.h"
#include "meta_io.h"
#include "quota.h"
#include "rgrp.h"
#include "trans.h"
#include "dir.h"
#include "util.h"
#include "ops_address.h"
/* This doesn't need to be that large as max 64 bit pointers in a 4k
* block is 512, so __u16 is fine for that. It saves stack space to
* keep it small.
*/
struct metapath {
struct buffer_head *mp_bh[GFS2_MAX_META_HEIGHT];
__u16 mp_list[GFS2_MAX_META_HEIGHT];
};
typedef int (*block_call_t) (struct gfs2_inode *ip, struct buffer_head *dibh,
struct buffer_head *bh, __be64 *top,
__be64 *bottom, unsigned int height,
void *data);
struct strip_mine {
int sm_first;
unsigned int sm_height;
};
/**
* gfs2_unstuffer_page - unstuff a stuffed inode into a block cached by a page
* @ip: the inode
* @dibh: the dinode buffer
* @block: the block number that was allocated
* @private: any locked page held by the caller process
*
* Returns: errno
*/
static int gfs2_unstuffer_page(struct gfs2_inode *ip, struct buffer_head *dibh,
u64 block, struct page *page)
{
struct inode *inode = &ip->i_inode;
struct buffer_head *bh;
int release = 0;
if (!page || page->index) {
page = grab_cache_page(inode->i_mapping, 0);
if (!page)
return -ENOMEM;
release = 1;
}
if (!PageUptodate(page)) {
void *kaddr = kmap(page);
memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode),
ip->i_di.di_size);
memset(kaddr + ip->i_di.di_size, 0,
PAGE_CACHE_SIZE - ip->i_di.di_size);
kunmap(page);
SetPageUptodate(page);
}
if (!page_has_buffers(page))
create_empty_buffers(page, 1 << inode->i_blkbits,
(1 << BH_Uptodate));
bh = page_buffers(page);
if (!buffer_mapped(bh))
map_bh(bh, inode->i_sb, block);
set_buffer_uptodate(bh);
if (!gfs2_is_jdata(ip))
mark_buffer_dirty(bh);
if (!gfs2_is_writeback(ip))
gfs2_trans_add_bh(ip->i_gl, bh, 0);
if (release) {
unlock_page(page);
page_cache_release(page);
}
return 0;
}
/**
* gfs2_unstuff_dinode - Unstuff a dinode when the data has grown too big
* @ip: The GFS2 inode to unstuff
* @unstuffer: the routine that handles unstuffing a non-zero length file
* @private: private data for the unstuffer
*
* This routine unstuffs a dinode and returns it to a "normal" state such
* that the height can be grown in the traditional way.
*
* Returns: errno
*/
int gfs2_unstuff_dinode(struct gfs2_inode *ip, struct page *page)
{
struct buffer_head *bh, *dibh;
struct gfs2_dinode *di;
u64 block = 0;
int isdir = gfs2_is_dir(ip);
int error;
down_write(&ip->i_rw_mutex);
error = gfs2_meta_inode_buffer(ip, &dibh);
if (error)
goto out;
if (ip->i_di.di_size) {
/* Get a free block, fill it with the stuffed data,
and write it out to disk */
if (isdir) {
block = gfs2_alloc_meta(ip);
error = gfs2_dir_get_new_buffer(ip, block, &bh);
if (error)
goto out_brelse;
gfs2_buffer_copy_tail(bh, sizeof(struct gfs2_meta_header),
dibh, sizeof(struct gfs2_dinode));
brelse(bh);
} else {
block = gfs2_alloc_data(ip);
error = gfs2_unstuffer_page(ip, dibh, block, page);
if (error)
goto out_brelse;
}
}
/* Set up the pointer to the new block */
gfs2_trans_add_bh(ip->i_gl, dibh, 1);
di = (struct gfs2_dinode *)dibh->b_data;
gfs2_buffer_clear_tail(dibh, sizeof(struct gfs2_dinode));
if (ip->i_di.di_size) {
*(__be64 *)(di + 1) = cpu_to_be64(block);
ip->i_di.di_blocks++;
gfs2_set_inode_blocks(&ip->i_inode);
di->di_blocks = cpu_to_be64(ip->i_di.di_blocks);
}
ip->i_height = 1;
di->di_height = cpu_to_be16(1);
out_brelse:
brelse(dibh);
out:
up_write(&ip->i_rw_mutex);
return error;
}
/**
* build_height - Build a metadata tree of the requested height
* @ip: The GFS2 inode
* @height: The height to build to
*
*
* Returns: errno
*/
static int build_height(struct inode *inode, struct metapath *mp, unsigned height)
{
struct gfs2_inode *ip = GFS2_I(inode);
unsigned new_height = height - ip->i_height;
struct buffer_head *dibh;
struct gfs2_dinode *di;
int error;
__be64 *bp;
u64 bn;
unsigned n;
if (height <= ip->i_height)
return 0;
error = gfs2_meta_inode_buffer(ip, &dibh);
if (error)
return error;
for(n = 0; n < new_height; n++) {
bn = gfs2_alloc_meta(ip);
mp->mp_bh[n] = gfs2_meta_new(ip->i_gl, bn);
gfs2_trans_add_bh(ip->i_gl, mp->mp_bh[n], 1);
}
n = 0;
bn = mp->mp_bh[0]->b_blocknr;
if (new_height > 1) {
for(; n < new_height-1; n++) {
gfs2_metatype_set(mp->mp_bh[n], GFS2_METATYPE_IN,
GFS2_FORMAT_IN);
gfs2_buffer_clear_tail(mp->mp_bh[n],
sizeof(struct gfs2_meta_header));
bp = (__be64 *)(mp->mp_bh[n]->b_data +
sizeof(struct gfs2_meta_header));
*bp = cpu_to_be64(mp->mp_bh[n+1]->b_blocknr);
brelse(mp->mp_bh[n]);
mp->mp_bh[n] = NULL;
}
}
gfs2_metatype_set(mp->mp_bh[n], GFS2_METATYPE_IN, GFS2_FORMAT_IN);
gfs2_buffer_copy_tail(mp->mp_bh[n], sizeof(struct gfs2_meta_header),
dibh, sizeof(struct gfs2_dinode));
brelse(mp->mp_bh[n]);
gfs2_trans_add_bh(ip->i_gl, dibh, 1);
di = (struct gfs2_dinode *)dibh->b_data;
gfs2_buffer_clear_tail(dibh, sizeof(struct gfs2_dinode));
*(__be64 *)(di + 1) = cpu_to_be64(bn);
ip->i_height += new_height;
ip->i_di.di_blocks += new_height;
gfs2_set_inode_blocks(&ip->i_inode);
di->di_height = cpu_to_be16(ip->i_height);
di->di_blocks = cpu_to_be64(ip->i_di.di_blocks);
brelse(dibh);
return error;
}
/**
* find_metapath - Find path through the metadata tree
* @ip: The inode pointer
* @mp: The metapath to return the result in
* @block: The disk block to look up
*
* This routine returns a struct metapath structure that defines a path
* through the metadata of inode "ip" to get to block "block".
*
* Example:
* Given: "ip" is a height 3 file, "offset" is 101342453, and this is a
* filesystem with a blocksize of 4096.
*
* find_metapath() would return a struct metapath structure set to:
* mp_offset = 101342453, mp_height = 3, mp_list[0] = 0, mp_list[1] = 48,
* and mp_list[2] = 165.
*
* That means that in order to get to the block containing the byte at
* offset 101342453, we would load the indirect block pointed to by pointer
* 0 in the dinode. We would then load the indirect block pointed to by
* pointer 48 in that indirect block. We would then load the data block
* pointed to by pointer 165 in that indirect block.
*
* ----------------------------------------
* | Dinode | |
* | | 4|
* | |0 1 2 3 4 5 9|
* | | 6|
* ----------------------------------------
* |
* |
* V
* ----------------------------------------
* | Indirect Block |
* | 5|
* | 4 4 4 4 4 5 5 1|
* |0 5 6 7 8 9 0 1 2|
* ----------------------------------------
* |
* |
* V
* ----------------------------------------
* | Indirect Block |
* | 1 1 1 1 1 5|
* | 6 6 6 6 6 1|
* |0 3 4 5 6 7 2|
* ----------------------------------------
* |
* |
* V
* ----------------------------------------
* | Data block containing offset |
* | 101342453 |
* | |
* | |
* ----------------------------------------
*
*/
static void find_metapath(struct gfs2_inode *ip, u64 block,
struct metapath *mp)
{
struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
unsigned int i;
for (i = ip->i_height; i--;)
mp->mp_list[i] = do_div(block, sdp->sd_inptrs);
}
/**
* metapointer - Return pointer to start of metadata in a buffer
* @height: The metadata height (0 = dinode)
* @mp: The metapath
*
* Return a pointer to the block number of the next height of the metadata
* tree given a buffer containing the pointer to the current height of the
* metadata tree.
*/
static inline __be64 *metapointer(int *boundary, unsigned int height,
const struct metapath *mp)
{
struct buffer_head *bh = mp->mp_bh[height];
unsigned int head_size = (height > 0) ?
sizeof(struct gfs2_meta_header) : sizeof(struct gfs2_dinode);
__be64 *ptr;
*boundary = 0;
ptr = ((__be64 *)(bh->b_data + head_size)) + mp->mp_list[height];
if (ptr + 1 == (__be64 *)(bh->b_data + bh->b_size))
*boundary = 1;
return ptr;
}
/**
* lookup_block - Get the next metadata block in metadata tree
* @ip: The GFS2 inode
* @height: The height of the tree (0 = dinode)
* @mp: The metapath
* @create: Non-zero if we may create a new meatdata block
* @new: Used to indicate if we did create a new metadata block
* @block: the returned disk block number
*
* Given a metatree, complete to a particular height, checks to see if the next
* height of the tree exists. If not the next height of the tree is created.
* The block number of the next height of the metadata tree is returned.
*
*/
static int lookup_block(struct gfs2_inode *ip, unsigned int height,
struct metapath *mp, int create,
int *new, u64 *block)
{
int boundary;
__be64 *ptr = metapointer(&boundary, height, mp);
if (*ptr) {
*block = be64_to_cpu(*ptr);
return boundary;
}
*block = 0;
if (!create)
return 0;
if (height == ip->i_height - 1 && !gfs2_is_dir(ip))
*block = gfs2_alloc_data(ip);
else
*block = gfs2_alloc_meta(ip);
gfs2_trans_add_bh(ip->i_gl, mp->mp_bh[height], 1);
*ptr = cpu_to_be64(*block);
ip->i_di.di_blocks++;
gfs2_set_inode_blocks(&ip->i_inode);
*new = 1;
return 0;
}
static int lookup_metapath(struct inode *inode, struct metapath *mp,
int create, int *new, u64 *dblock)
{
struct buffer_head *bh;
struct gfs2_inode *ip = GFS2_I(inode);
unsigned int end_of_metadata = ip->i_height - 1;
unsigned int x;
int ret = gfs2_meta_inode_buffer(ip, &bh);
if (ret)
return ret;
mp->mp_bh[0] = bh;
for (x = 0; x < end_of_metadata; x++) {
lookup_block(ip, x, mp, create, new, dblock);
if (!dblock)
return 0;
ret = gfs2_meta_indirect_buffer(ip, x+1, *dblock, *new, &mp->mp_bh[x+1]);
if (ret)
return ret;
}
return lookup_block(ip, end_of_metadata, mp, create, new, dblock);
}
static void release_metapath(struct metapath *mp)
{
int i;
for (i = 0; i < GFS2_MAX_META_HEIGHT; i++)
if (mp->mp_bh[i])
brelse(mp->mp_bh[i]);
}
static inline void bmap_lock(struct inode *inode, int create)
{
struct gfs2_inode *ip = GFS2_I(inode);
if (create)
down_write(&ip->i_rw_mutex);
else
down_read(&ip->i_rw_mutex);
}
static inline void bmap_unlock(struct inode *inode, int create)
{
struct gfs2_inode *ip = GFS2_I(inode);
if (create)
up_write(&ip->i_rw_mutex);
else
up_read(&ip->i_rw_mutex);
}
/**
* 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
*
* Find the block number on the current device which corresponds to an
* inode's block. If the block had to be created, "new" will be set.
*
* 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 gfs2_sbd *sdp = GFS2_SB(inode);
unsigned int bsize = sdp->sd_sb.sb_bsize;
int error = 0;
int new = 0;
u64 dblock = 0;
int boundary;
unsigned int maxlen = bh_map->b_size >> inode->i_blkbits;
struct metapath mp;
u64 size;
const u64 *arr = sdp->sd_heightsize;
BUG_ON(maxlen == 0);
if (gfs2_assert_warn(sdp, !gfs2_is_stuffed(ip)))
return 0;
memset(mp.mp_bh, 0, sizeof(mp.mp_bh));
bmap_lock(inode, create);
clear_buffer_mapped(bh_map);
clear_buffer_new(bh_map);
clear_buffer_boundary(bh_map);
if (gfs2_is_dir(ip)) {
bsize = sdp->sd_jbsize;
arr = sdp->sd_jheightsize;
}
size = (lblock + 1) * bsize;
if (size > arr[ip->i_height]) {
u8 height = ip->i_height;
if (!create)
goto out_ok;
while (size > arr[height])
height++;
error = build_height(inode, &mp, height);
if (error)
goto out_fail;
}
find_metapath(ip, lblock, &mp);
error = lookup_metapath(inode, &mp, create, &new, &dblock);
if (error < 0)
goto out_fail;
boundary = error;
if (dblock) {
map_bh(bh_map, inode->i_sb, dblock);
if (boundary)
set_buffer_boundary(bh_map);
if (new) {
gfs2_trans_add_bh(ip->i_gl, mp.mp_bh[0], 1);
gfs2_dinode_out(ip, mp.mp_bh[0]->b_data);
set_buffer_new(bh_map);
goto out_ok;
}
while(--maxlen && !buffer_boundary(bh_map)) {
u64 eblock;
mp.mp_list[ip->i_height - 1]++;
boundary = lookup_block(ip, ip->i_height - 1, &mp, 0, &new, &eblock);
if (eblock != ++dblock)
break;
bh_map->b_size += (1 << inode->i_blkbits);
if (boundary)
set_buffer_boundary(bh_map);
}
}
out_ok:
error = 0;
out_fail:
release_metapath(&mp);
bmap_unlock(inode, create);
return error;
}
/*
* Deprecated: do not use in new code
*/
int gfs2_extent_map(struct inode *inode, u64 lblock, int *new, u64 *dblock, unsigned *extlen)
{
struct buffer_head bh = { .b_state = 0, .b_blocknr = 0 };
int ret;
int create = *new;
BUG_ON(!extlen);
BUG_ON(!dblock);
BUG_ON(!new);
bh.b_size = 1 << (inode->i_blkbits + 5);
ret = gfs2_block_map(inode, lblock, &bh, create);
*extlen = bh.b_size >> inode->i_blkbits;
*dblock = bh.b_blocknr;
if (buffer_new(&bh))
*new = 1;
else
*new = 0;
return ret;
}
/**
* recursive_scan - recursively scan through the end of a file
* @ip: the inode
* @dibh: the dinode buffer
* @mp: the path through the metadata to the point to start
* @height: the height the recursion is at
* @block: the indirect block to look at
* @first: 1 if this is the first block
* @bc: the call to make for each piece of metadata
* @data: data opaque to this function to pass to @bc
*
* When this is first called @height and @block should be zero and
* @first should be 1.
*
* Returns: errno
*/
static int recursive_scan(struct gfs2_inode *ip, struct buffer_head *dibh,
struct metapath *mp, unsigned int height,
u64 block, int first, block_call_t bc,
void *data)
{
struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
struct buffer_head *bh = NULL;
__be64 *top, *bottom;
u64 bn;
int error;
int mh_size = sizeof(struct gfs2_meta_header);
if (!height) {
error = gfs2_meta_inode_buffer(ip, &bh);
if (error)
return error;
dibh = bh;
top = (__be64 *)(bh->b_data + sizeof(struct gfs2_dinode)) + mp->mp_list[0];
bottom = (__be64 *)(bh->b_data + sizeof(struct gfs2_dinode)) + sdp->sd_diptrs;
} else {
error = gfs2_meta_indirect_buffer(ip, height, block, 0, &bh);
if (error)
return error;
top = (__be64 *)(bh->b_data + mh_size) +
(first ? mp->mp_list[height] : 0);
bottom = (__be64 *)(bh->b_data + mh_size) + sdp->sd_inptrs;
}
error = bc(ip, dibh, bh, top, bottom, height, data);
if (error)
goto out;
if (height < ip->i_height - 1)
for (; top < bottom; top++, first = 0) {
if (!*top)
continue;
bn = be64_to_cpu(*top);
error = recursive_scan(ip, dibh, mp, height + 1, bn,
first, bc, data);
if (error)
break;
}
out:
brelse(bh);
return error;
}
/**
* do_strip - Look for a layer a particular layer of the file and strip it off
* @ip: the inode
* @dibh: the dinode buffer
* @bh: A buffer of pointers
* @top: The first pointer in the buffer
* @bottom: One more than the last pointer
* @height: the height this buffer is at
* @data: a pointer to a struct strip_mine
*
* Returns: errno
*/
static int do_strip(struct gfs2_inode *ip, struct buffer_head *dibh,
struct buffer_head *bh, __be64 *top, __be64 *bottom,
unsigned int height, void *data)
{
struct strip_mine *sm = data;
struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
struct gfs2_rgrp_list rlist;
u64 bn, bstart;
u32 blen;
__be64 *p;
unsigned int rg_blocks = 0;
int metadata;
unsigned int revokes = 0;
int x;
int error;
if (!*top)
sm->sm_first = 0;
if (height != sm->sm_height)
return 0;
if (sm->sm_first) {
top++;
sm->sm_first = 0;
}
metadata = (height != ip->i_height - 1);
if (metadata)
revokes = (height) ? sdp->sd_inptrs : sdp->sd_diptrs;
error = gfs2_rindex_hold(sdp, &ip->i_alloc->al_ri_gh);
if (error)
return error;
memset(&rlist, 0, sizeof(struct gfs2_rgrp_list));
bstart = 0;
blen = 0;
for (p = top; p < bottom; p++) {
if (!*p)
continue;
bn = be64_to_cpu(*p);
if (bstart + blen == bn)
blen++;
else {
if (bstart)
gfs2_rlist_add(sdp, &rlist, bstart);
bstart = bn;
blen = 1;
}
}
if (bstart)
gfs2_rlist_add(sdp, &rlist, bstart);
else
goto out; /* Nothing to do */
gfs2_rlist_alloc(&rlist, LM_ST_EXCLUSIVE);
for (x = 0; x < rlist.rl_rgrps; x++) {
struct gfs2_rgrpd *rgd;
rgd = rlist.rl_ghs[x].gh_gl->gl_object;
rg_blocks += rgd->rd_length;
}
error = gfs2_glock_nq_m(rlist.rl_rgrps, rlist.rl_ghs);
if (error)
goto out_rlist;
error = gfs2_trans_begin(sdp, rg_blocks + RES_DINODE +
RES_INDIRECT + RES_STATFS + RES_QUOTA,
revokes);
if (error)
goto out_rg_gunlock;
down_write(&ip->i_rw_mutex);
gfs2_trans_add_bh(ip->i_gl, dibh, 1);
gfs2_trans_add_bh(ip->i_gl, bh, 1);
bstart = 0;
blen = 0;
for (p = top; p < bottom; p++) {
if (!*p)
continue;
bn = be64_to_cpu(*p);
if (bstart + blen == bn)
blen++;
else {
if (bstart) {
if (metadata)
gfs2_free_meta(ip, bstart, blen);
else
gfs2_free_data(ip, bstart, blen);
}
bstart = bn;
blen = 1;
}
*p = 0;
if (!ip->i_di.di_blocks)
gfs2_consist_inode(ip);
ip->i_di.di_blocks--;
gfs2_set_inode_blocks(&ip->i_inode);
}
if (bstart) {
if (metadata)
gfs2_free_meta(ip, bstart, blen);
else
gfs2_free_data(ip, bstart, blen);
}
ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;
gfs2_dinode_out(ip, dibh->b_data);
up_write(&ip->i_rw_mutex);
gfs2_trans_end(sdp);
out_rg_gunlock:
gfs2_glock_dq_m(rlist.rl_rgrps, rlist.rl_ghs);
out_rlist:
gfs2_rlist_free(&rlist);
out:
gfs2_glock_dq_uninit(&ip->i_alloc->al_ri_gh);
return error;
}
/**
* do_grow - Make a file look bigger than it is
* @ip: the inode
* @size: the size to set the file to
*
* Called with an exclusive lock on @ip.
*
* Returns: errno
*/
static int do_grow(struct gfs2_inode *ip, u64 size)
{
struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
struct gfs2_alloc *al;
struct buffer_head *dibh;
int error;
al = gfs2_alloc_get(ip);
error = gfs2_quota_lock(ip, NO_QUOTA_CHANGE, NO_QUOTA_CHANGE);
if (error)
goto out;
error = gfs2_quota_check(ip, ip->i_inode.i_uid, ip->i_inode.i_gid);
if (error)
goto out_gunlock_q;
al->al_requested = sdp->sd_max_height + RES_DATA;
error = gfs2_inplace_reserve(ip);
if (error)
goto out_gunlock_q;
error = gfs2_trans_begin(sdp,
sdp->sd_max_height + al->al_rgd->rd_length +
RES_JDATA + RES_DINODE + RES_STATFS + RES_QUOTA, 0);
if (error)
goto out_ipres;
if (size > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)) {
const u64 *arr = sdp->sd_heightsize;
if (gfs2_is_stuffed(ip)) {
error = gfs2_unstuff_dinode(ip, NULL);
if (error)
goto out_end_trans;
}
down_write(&ip->i_rw_mutex);
if (size > arr[ip->i_height]) {
struct metapath mp;
u8 height = ip->i_height;
while(size > arr[height])
height++;
error = build_height(&ip->i_inode, &mp, height);
}
up_write(&ip->i_rw_mutex);
if (error)
goto out_end_trans;
}
ip->i_di.di_size = size;
ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;
error = gfs2_meta_inode_buffer(ip, &dibh);
if (error)
goto out_end_trans;
gfs2_trans_add_bh(ip->i_gl, dibh, 1);
gfs2_dinode_out(ip, dibh->b_data);
brelse(dibh);
out_end_trans:
gfs2_trans_end(sdp);
out_ipres:
gfs2_inplace_release(ip);
out_gunlock_q:
gfs2_quota_unlock(ip);
out:
gfs2_alloc_put(ip);
return error;
}
/**
* gfs2_block_truncate_page - Deal with zeroing out data for truncate
*
* This is partly borrowed from ext3.
*/
static int gfs2_block_truncate_page(struct address_space *mapping)
{
struct inode *inode = mapping->host;
struct gfs2_inode *ip = GFS2_I(inode);
loff_t from = inode->i_size;
unsigned long index = from >> PAGE_CACHE_SHIFT;
unsigned offset = from & (PAGE_CACHE_SIZE-1);
unsigned blocksize, iblock, length, pos;
struct buffer_head *bh;
struct page *page;
int err;
page = grab_cache_page(mapping, index);
if (!page)
return 0;
blocksize = inode->i_sb->s_blocksize;
length = blocksize - (offset & (blocksize - 1));
iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
if (!page_has_buffers(page))
create_empty_buffers(page, blocksize, 0);
/* Find the buffer that contains "offset" */
bh = page_buffers(page);
pos = blocksize;
while (offset >= pos) {
bh = bh->b_this_page;
iblock++;
pos += blocksize;
}
err = 0;
if (!buffer_mapped(bh)) {
gfs2_block_map(inode, iblock, bh, 0);
/* unmapped? It's a hole - nothing to do */
if (!buffer_mapped(bh))
goto unlock;
}
/* Ok, it's mapped. Make sure it's up-to-date */
if (PageUptodate(page))
set_buffer_uptodate(bh);
if (!buffer_uptodate(bh)) {
err = -EIO;
ll_rw_block(READ, 1, &bh);
wait_on_buffer(bh);
/* Uhhuh. Read error. Complain and punt. */
if (!buffer_uptodate(bh))
goto unlock;
err = 0;
}
if (!gfs2_is_writeback(ip))
gfs2_trans_add_bh(ip->i_gl, bh, 0);
zero_user(page, offset, length);
unlock:
unlock_page(page);
page_cache_release(page);
return err;
}
static int trunc_start(struct gfs2_inode *ip, u64 size)
{
struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
struct buffer_head *dibh;
int journaled = gfs2_is_jdata(ip);
int error;
error = gfs2_trans_begin(sdp,
RES_DINODE + (journaled ? RES_JDATA : 0), 0);
if (error)
return error;
error = gfs2_meta_inode_buffer(ip, &dibh);
if (error)
goto out;
if (gfs2_is_stuffed(ip)) {
ip->i_di.di_size = size;
ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;
gfs2_trans_add_bh(ip->i_gl, dibh, 1);
gfs2_dinode_out(ip, dibh->b_data);
gfs2_buffer_clear_tail(dibh, sizeof(struct gfs2_dinode) + size);
error = 1;
} else {
if (size & (u64)(sdp->sd_sb.sb_bsize - 1))
error = gfs2_block_truncate_page(ip->i_inode.i_mapping);
if (!error) {
ip->i_di.di_size = size;
ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;
ip->i_di.di_flags |= GFS2_DIF_TRUNC_IN_PROG;
gfs2_trans_add_bh(ip->i_gl, dibh, 1);
gfs2_dinode_out(ip, dibh->b_data);
}
}
brelse(dibh);
out:
gfs2_trans_end(sdp);
return error;
}
static int trunc_dealloc(struct gfs2_inode *ip, u64 size)
{
unsigned int height = ip->i_height;
u64 lblock;
struct metapath mp;
int error;
if (!size)
lblock = 0;
else
lblock = (size - 1) >> GFS2_SB(&ip->i_inode)->sd_sb.sb_bsize_shift;
find_metapath(ip, lblock, &mp);
gfs2_alloc_get(ip);
error = gfs2_quota_hold(ip, NO_QUOTA_CHANGE, NO_QUOTA_CHANGE);
if (error)
goto out;
while (height--) {
struct strip_mine sm;
sm.sm_first = !!size;
sm.sm_height = height;
error = recursive_scan(ip, NULL, &mp, 0, 0, 1, do_strip, &sm);
if (error)
break;
}
gfs2_quota_unhold(ip);
out:
gfs2_alloc_put(ip);
return error;
}
static int trunc_end(struct gfs2_inode *ip)
{
struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
struct buffer_head *dibh;
int error;
error = gfs2_trans_begin(sdp, RES_DINODE, 0);
if (error)
return error;
down_write(&ip->i_rw_mutex);
error = gfs2_meta_inode_buffer(ip, &dibh);
if (error)
goto out;
if (!ip->i_di.di_size) {
ip->i_height = 0;
ip->i_goal = ip->i_no_addr;
gfs2_buffer_clear_tail(dibh, sizeof(struct gfs2_dinode));
}
ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;
ip->i_di.di_flags &= ~GFS2_DIF_TRUNC_IN_PROG;
gfs2_trans_add_bh(ip->i_gl, dibh, 1);
gfs2_dinode_out(ip, dibh->b_data);
brelse(dibh);
out:
up_write(&ip->i_rw_mutex);
gfs2_trans_end(sdp);
return error;
}
/**
* do_shrink - make a file smaller
* @ip: the inode
* @size: the size to make the file
* @truncator: function to truncate the last partial block
*
* Called with an exclusive lock on @ip.
*
* Returns: errno
*/
static int do_shrink(struct gfs2_inode *ip, u64 size)
{
int error;
error = trunc_start(ip, size);
if (error < 0)
return error;
if (error > 0)
return 0;
error = trunc_dealloc(ip, size);
if (!error)
error = trunc_end(ip);
return error;
}
static int do_touch(struct gfs2_inode *ip, u64 size)
{
struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
struct buffer_head *dibh;
int error;
error = gfs2_trans_begin(sdp, RES_DINODE, 0);
if (error)
return error;
down_write(&ip->i_rw_mutex);
error = gfs2_meta_inode_buffer(ip, &dibh);
if (error)
goto do_touch_out;
ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;
gfs2_trans_add_bh(ip->i_gl, dibh, 1);
gfs2_dinode_out(ip, dibh->b_data);
brelse(dibh);
do_touch_out:
up_write(&ip->i_rw_mutex);
gfs2_trans_end(sdp);
return error;
}
/**
* gfs2_truncatei - make a file a given size
* @ip: the inode
* @size: the size to make the file
* @truncator: function to truncate the last partial block
*
* The file size can grow, shrink, or stay the same size.
*
* Returns: errno
*/
int gfs2_truncatei(struct gfs2_inode *ip, u64 size)
{
int error;
if (gfs2_assert_warn(GFS2_SB(&ip->i_inode), S_ISREG(ip->i_inode.i_mode)))
return -EINVAL;
if (size > ip->i_di.di_size)
error = do_grow(ip, size);
else if (size < ip->i_di.di_size)
error = do_shrink(ip, size);
else
/* update time stamps */
error = do_touch(ip, size);
return error;
}
int gfs2_truncatei_resume(struct gfs2_inode *ip)
{
int error;
error = trunc_dealloc(ip, ip->i_di.di_size);
if (!error)
error = trunc_end(ip);
return error;
}
int gfs2_file_dealloc(struct gfs2_inode *ip)
{
return trunc_dealloc(ip, 0);
}
/**
* gfs2_write_calc_reserv - calculate number of blocks needed to write to a file
* @ip: the file
* @len: the number of bytes to be written to the file
* @data_blocks: returns the number of data blocks required
* @ind_blocks: returns the number of indirect blocks required
*
*/
void gfs2_write_calc_reserv(struct gfs2_inode *ip, unsigned int len,
unsigned int *data_blocks, unsigned int *ind_blocks)
{
struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
unsigned int tmp;
if (gfs2_is_dir(ip)) {
*data_blocks = DIV_ROUND_UP(len, sdp->sd_jbsize) + 2;
*ind_blocks = 3 * (sdp->sd_max_jheight - 1);
} else {
*data_blocks = (len >> sdp->sd_sb.sb_bsize_shift) + 3;
*ind_blocks = 3 * (sdp->sd_max_height - 1);
}
for (tmp = *data_blocks; tmp > sdp->sd_diptrs;) {
tmp = DIV_ROUND_UP(tmp, sdp->sd_inptrs);
*ind_blocks += tmp;
}
}
/**
* gfs2_write_alloc_required - figure out if a write will require an allocation
* @ip: the file being written to
* @offset: the offset to write to
* @len: the number of bytes being written
* @alloc_required: set to 1 if an alloc is required, 0 otherwise
*
* Returns: errno
*/
int gfs2_write_alloc_required(struct gfs2_inode *ip, u64 offset,
unsigned int len, int *alloc_required)
{
struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
struct buffer_head bh;
unsigned int shift;
u64 lblock, lblock_stop, size;
*alloc_required = 0;
if (!len)
return 0;
if (gfs2_is_stuffed(ip)) {
if (offset + len >
sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode))
*alloc_required = 1;
return 0;
}
*alloc_required = 1;
shift = sdp->sd_sb.sb_bsize_shift;
if (gfs2_is_dir(ip)) {
unsigned int bsize = sdp->sd_jbsize;
lblock = offset;
do_div(lblock, bsize);
lblock_stop = offset + len + bsize - 1;
do_div(lblock_stop, bsize);
} else {
u64 end_of_file = (ip->i_di.di_size + sdp->sd_sb.sb_bsize - 1) >> shift;
lblock = offset >> shift;
lblock_stop = (offset + len + sdp->sd_sb.sb_bsize - 1) >> shift;
if (lblock_stop > end_of_file)
return 0;
}
size = (lblock_stop - lblock) << shift;
do {
bh.b_state = 0;
bh.b_size = size;
gfs2_block_map(&ip->i_inode, lblock, &bh, 0);
if (!buffer_mapped(&bh))
return 0;
size -= bh.b_size;
lblock += (bh.b_size >> ip->i_inode.i_blkbits);
} while(size > 0);
*alloc_required = 0;
return 0;
}
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