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linux/fs/udf/truncate.c
Jan Kara 74584ae509 udf: fix possible leakage of blocks 
We have to take care that when we call udf_discard_prealloc() from
udf_clear_inode() we have to write inode ourselves afterwards (otherwise,
some changes might be lost leading to leakage of blocks, use of free blocks
or improperly aligned extents).

Also udf_discard_prealloc() does two different things - it removes
preallocated blocks and truncates the last extent to exactly match i_size.
We move the latter functionality to udf_truncate_tail_extent(), call
udf_discard_prealloc() when last reference to a file is dropped and call
udf_truncate_tail_extent() when inode is being removed from inode cache
(udf_clear_inode() call).

We cannot call udf_truncate_tail_extent() earlier as subsequent open+write
would find the last block of the file mapped and happily write to the end
of it, although the last extent says it's shorter.

[akpm@linux-foundation.org: Make checkpatch.pl happier]
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Eric Sandeen <sandeen@sandeen.net>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-06-16 13:16:16 -07:00

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/*
* truncate.c
*
* PURPOSE
* Truncate handling routines for the OSTA-UDF(tm) filesystem.
*
* COPYRIGHT
* This file is distributed under the terms of the GNU General Public
* License (GPL). Copies of the GPL can be obtained from:
* ftp://prep.ai.mit.edu/pub/gnu/GPL
* Each contributing author retains all rights to their own work.
*
* (C) 1999-2004 Ben Fennema
* (C) 1999 Stelias Computing Inc
*
* HISTORY
*
* 02/24/99 blf Created.
*
*/
#include "udfdecl.h"
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/udf_fs.h>
#include <linux/buffer_head.h>
#include "udf_i.h"
#include "udf_sb.h"
static void extent_trunc(struct inode * inode, struct extent_position *epos,
kernel_lb_addr eloc, int8_t etype, uint32_t elen, uint32_t nelen)
{
kernel_lb_addr neloc = { 0, 0 };
int last_block = (elen + inode->i_sb->s_blocksize - 1) >> inode->i_sb->s_blocksize_bits;
int first_block = (nelen + inode->i_sb->s_blocksize - 1) >> inode->i_sb->s_blocksize_bits;
if (nelen)
{
if (etype == (EXT_NOT_RECORDED_ALLOCATED >> 30))
{
udf_free_blocks(inode->i_sb, inode, eloc, 0, last_block);
etype = (EXT_NOT_RECORDED_NOT_ALLOCATED >> 30);
}
else
neloc = eloc;
nelen = (etype << 30) | nelen;
}
if (elen != nelen)
{
udf_write_aext(inode, epos, neloc, nelen, 0);
if (last_block - first_block > 0)
{
if (etype == (EXT_RECORDED_ALLOCATED >> 30))
mark_inode_dirty(inode);
if (etype != (EXT_NOT_RECORDED_NOT_ALLOCATED >> 30))
udf_free_blocks(inode->i_sb, inode, eloc, first_block, last_block - first_block);
}
}
}
/*
* Truncate the last extent to match i_size. This function assumes
* that preallocation extent is already truncated.
*/
void udf_truncate_tail_extent(struct inode *inode)
{
struct extent_position epos = { NULL, 0, {0, 0}};
kernel_lb_addr eloc;
uint32_t elen, nelen;
uint64_t lbcount = 0;
int8_t etype = -1, netype;
int adsize;
if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_IN_ICB ||
inode->i_size == UDF_I_LENEXTENTS(inode))
return;
/* Are we going to delete the file anyway? */
if (inode->i_nlink == 0)
return;
if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_SHORT)
adsize = sizeof(short_ad);
else if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_LONG)
adsize = sizeof(long_ad);
else
BUG();
/* Find the last extent in the file */
while ((netype = udf_next_aext(inode, &epos, &eloc, &elen, 1)) != -1)
{
etype = netype;
lbcount += elen;
if (lbcount > inode->i_size) {
if (lbcount - inode->i_size >= inode->i_sb->s_blocksize)
printk(KERN_WARNING
"udf_truncate_tail_extent(): Too long "
"extent after EOF in inode %u: i_size: "
"%Ld lbcount: %Ld extent %u+%u\n",
(unsigned)inode->i_ino,
(long long)inode->i_size,
(long long)lbcount,
(unsigned)eloc.logicalBlockNum,
(unsigned)elen);
nelen = elen - (lbcount - inode->i_size);
epos.offset -= adsize;
extent_trunc(inode, &epos, eloc, etype, elen, nelen);
epos.offset += adsize;
if (udf_next_aext(inode, &epos, &eloc, &elen, 1) != -1)
printk(KERN_ERR "udf_truncate_tail_extent(): "
"Extent after EOF in inode %u.\n",
(unsigned)inode->i_ino);
break;
}
}
/* This inode entry is in-memory only and thus we don't have to mark
* the inode dirty */
UDF_I_LENEXTENTS(inode) = inode->i_size;
brelse(epos.bh);
}
void udf_discard_prealloc(struct inode *inode)
{
struct extent_position epos = { NULL, 0, {0, 0}};
kernel_lb_addr eloc;
uint32_t elen;
uint64_t lbcount = 0;
int8_t etype = -1, netype;
int adsize;
if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_IN_ICB ||
inode->i_size == UDF_I_LENEXTENTS(inode))
return;
if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_SHORT)
adsize = sizeof(short_ad);
else if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_LONG)
adsize = sizeof(long_ad);
else
adsize = 0;
epos.block = UDF_I_LOCATION(inode);
/* Find the last extent in the file */
while ((netype = udf_next_aext(inode, &epos, &eloc, &elen, 1)) != -1) {
etype = netype;
lbcount += elen;
}
if (etype == (EXT_NOT_RECORDED_ALLOCATED >> 30)) {
epos.offset -= adsize;
lbcount -= elen;
extent_trunc(inode, &epos, eloc, etype, elen, 0);
if (!epos.bh) {
UDF_I_LENALLOC(inode) = epos.offset - udf_file_entry_alloc_offset(inode);
mark_inode_dirty(inode);
} else {
struct allocExtDesc *aed = (struct allocExtDesc *)(epos.bh->b_data);
aed->lengthAllocDescs = cpu_to_le32(epos.offset - sizeof(struct allocExtDesc));
if (!UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_STRICT) || UDF_SB_UDFREV(inode->i_sb) >= 0x0201)
udf_update_tag(epos.bh->b_data, epos.offset);
else
udf_update_tag(epos.bh->b_data, sizeof(struct allocExtDesc));
mark_buffer_dirty_inode(epos.bh, inode);
}
}
/* This inode entry is in-memory only and thus we don't have to mark
* the inode dirty */
UDF_I_LENEXTENTS(inode) = lbcount;
brelse(epos.bh);
}
void udf_truncate_extents(struct inode * inode)
{
struct extent_position epos;
kernel_lb_addr eloc, neloc = { 0, 0 };
uint32_t elen, nelen = 0, indirect_ext_len = 0, lenalloc;
int8_t etype;
struct super_block *sb = inode->i_sb;
sector_t first_block = inode->i_size >> sb->s_blocksize_bits, offset;
loff_t byte_offset;
int adsize;
if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_SHORT)
adsize = sizeof(short_ad);
else if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_LONG)
adsize = sizeof(long_ad);
else
BUG();
etype = inode_bmap(inode, first_block, &epos, &eloc, &elen, &offset);
byte_offset = (offset << sb->s_blocksize_bits) + (inode->i_size & (sb->s_blocksize-1));
if (etype != -1)
{
epos.offset -= adsize;
extent_trunc(inode, &epos, eloc, etype, elen, byte_offset);
epos.offset += adsize;
if (byte_offset)
lenalloc = epos.offset;
else
lenalloc = epos.offset - adsize;
if (!epos.bh)
lenalloc -= udf_file_entry_alloc_offset(inode);
else
lenalloc -= sizeof(struct allocExtDesc);
while ((etype = udf_current_aext(inode, &epos, &eloc, &elen, 0)) != -1)
{
if (etype == (EXT_NEXT_EXTENT_ALLOCDECS >> 30))
{
udf_write_aext(inode, &epos, neloc, nelen, 0);
if (indirect_ext_len)
{
/* We managed to free all extents in the
* indirect extent - free it too */
if (!epos.bh)
BUG();
udf_free_blocks(sb, inode, epos.block, 0, indirect_ext_len);
}
else
{
if (!epos.bh)
{
UDF_I_LENALLOC(inode) = lenalloc;
mark_inode_dirty(inode);
}
else
{
struct allocExtDesc *aed = (struct allocExtDesc *)(epos.bh->b_data);
aed->lengthAllocDescs = cpu_to_le32(lenalloc);
if (!UDF_QUERY_FLAG(sb, UDF_FLAG_STRICT) || UDF_SB_UDFREV(sb) >= 0x0201)
udf_update_tag(epos.bh->b_data, lenalloc +
sizeof(struct allocExtDesc));
else
udf_update_tag(epos.bh->b_data, sizeof(struct allocExtDesc));
mark_buffer_dirty_inode(epos.bh, inode);
}
}
brelse(epos.bh);
epos.offset = sizeof(struct allocExtDesc);
epos.block = eloc;
epos.bh = udf_tread(sb, udf_get_lb_pblock(sb, eloc, 0));
if (elen)
indirect_ext_len = (elen +
sb->s_blocksize - 1) >>
sb->s_blocksize_bits;
else
indirect_ext_len = 1;
}
else
{
extent_trunc(inode, &epos, eloc, etype, elen, 0);
epos.offset += adsize;
}
}
if (indirect_ext_len)
{
if (!epos.bh)
BUG();
udf_free_blocks(sb, inode, epos.block, 0, indirect_ext_len);
}
else
{
if (!epos.bh)
{
UDF_I_LENALLOC(inode) = lenalloc;
mark_inode_dirty(inode);
}
else
{
struct allocExtDesc *aed = (struct allocExtDesc *)(epos.bh->b_data);
aed->lengthAllocDescs = cpu_to_le32(lenalloc);
if (!UDF_QUERY_FLAG(sb, UDF_FLAG_STRICT) || UDF_SB_UDFREV(sb) >= 0x0201)
udf_update_tag(epos.bh->b_data, lenalloc +
sizeof(struct allocExtDesc));
else
udf_update_tag(epos.bh->b_data, sizeof(struct allocExtDesc));
mark_buffer_dirty_inode(epos.bh, inode);
}
}
}
else if (inode->i_size)
{
if (byte_offset)
{
kernel_long_ad extent;
/*
* OK, there is not extent covering inode->i_size and
* no extent above inode->i_size => truncate is
* extending the file by 'offset' blocks.
*/
if ((!epos.bh && epos.offset == udf_file_entry_alloc_offset(inode)) ||
(epos.bh && epos.offset == sizeof(struct allocExtDesc))) {
/* File has no extents at all or has empty last
* indirect extent! Create a fake extent... */
extent.extLocation.logicalBlockNum = 0;
extent.extLocation.partitionReferenceNum = 0;
extent.extLength = EXT_NOT_RECORDED_NOT_ALLOCATED;
}
else {
epos.offset -= adsize;
etype = udf_next_aext(inode, &epos,
&extent.extLocation, &extent.extLength, 0);
extent.extLength |= etype << 30;
}
udf_extend_file(inode, &epos, &extent, offset+((inode->i_size & (sb->s_blocksize-1)) != 0));
}
}
UDF_I_LENEXTENTS(inode) = inode->i_size;
brelse(epos.bh);
}
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