linux/fs/xfs/xfs_attr_inactive.c
Brian Foster f35c5e10c6 xfs: reinit btree pointer on attr tree inactivation walk
xfs_attr3_root_inactive() walks the attr fork tree to invalidate the
associated blocks. xfs_attr3_node_inactive() recursively descends
from internal blocks to leaf blocks, caching block address values
along the way to revisit parent blocks, locate the next entry and
descend down that branch of the tree.

The code that attempts to reread the parent block is unsafe because
it assumes that the local xfs_da_node_entry pointer remains valid
after an xfs_trans_brelse() and re-read of the parent buffer. Under
heavy memory pressure, it is possible that the buffer has been
reclaimed and reallocated by the time the parent block is reread.
This means that 'btree' can point to an invalid memory address, lead
to a random/garbage value for child_fsb and cause the subsequent
read of the attr fork to go off the rails and return a NULL buffer
for an attr fork offset that is most likely not allocated.

Note that this problem can be manufactured by setting
XFS_ATTR_BTREE_REF to 0 to prevent LRU caching of attr buffers,
creating a file with a multi-level attr fork and removing it to
trigger inactivation.

To address this problem, reinit the node/btree pointers to the
parent buffer after it has been re-read. This ensures btree points
to a valid record and allows the walk to proceed.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2017-10-11 10:21:07 -07:00

462 lines
11 KiB
C

/*
* Copyright (c) 2000-2005 Silicon Graphics, Inc.
* Copyright (c) 2013 Red Hat, Inc.
* All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it would be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_bit.h"
#include "xfs_mount.h"
#include "xfs_da_format.h"
#include "xfs_da_btree.h"
#include "xfs_inode.h"
#include "xfs_alloc.h"
#include "xfs_attr_remote.h"
#include "xfs_trans.h"
#include "xfs_inode_item.h"
#include "xfs_bmap.h"
#include "xfs_attr.h"
#include "xfs_attr_leaf.h"
#include "xfs_error.h"
#include "xfs_quota.h"
#include "xfs_trace.h"
#include "xfs_dir2.h"
/*
* Look at all the extents for this logical region,
* invalidate any buffers that are incore/in transactions.
*/
STATIC int
xfs_attr3_leaf_freextent(
struct xfs_trans **trans,
struct xfs_inode *dp,
xfs_dablk_t blkno,
int blkcnt)
{
struct xfs_bmbt_irec map;
struct xfs_buf *bp;
xfs_dablk_t tblkno;
xfs_daddr_t dblkno;
int tblkcnt;
int dblkcnt;
int nmap;
int error;
/*
* Roll through the "value", invalidating the attribute value's
* blocks.
*/
tblkno = blkno;
tblkcnt = blkcnt;
while (tblkcnt > 0) {
/*
* Try to remember where we decided to put the value.
*/
nmap = 1;
error = xfs_bmapi_read(dp, (xfs_fileoff_t)tblkno, tblkcnt,
&map, &nmap, XFS_BMAPI_ATTRFORK);
if (error) {
return error;
}
ASSERT(nmap == 1);
ASSERT(map.br_startblock != DELAYSTARTBLOCK);
/*
* If it's a hole, these are already unmapped
* so there's nothing to invalidate.
*/
if (map.br_startblock != HOLESTARTBLOCK) {
dblkno = XFS_FSB_TO_DADDR(dp->i_mount,
map.br_startblock);
dblkcnt = XFS_FSB_TO_BB(dp->i_mount,
map.br_blockcount);
bp = xfs_trans_get_buf(*trans,
dp->i_mount->m_ddev_targp,
dblkno, dblkcnt, 0);
if (!bp)
return -ENOMEM;
xfs_trans_binval(*trans, bp);
/*
* Roll to next transaction.
*/
error = xfs_trans_roll_inode(trans, dp);
if (error)
return error;
}
tblkno += map.br_blockcount;
tblkcnt -= map.br_blockcount;
}
return 0;
}
/*
* Invalidate all of the "remote" value regions pointed to by a particular
* leaf block.
* Note that we must release the lock on the buffer so that we are not
* caught holding something that the logging code wants to flush to disk.
*/
STATIC int
xfs_attr3_leaf_inactive(
struct xfs_trans **trans,
struct xfs_inode *dp,
struct xfs_buf *bp)
{
struct xfs_attr_leafblock *leaf;
struct xfs_attr3_icleaf_hdr ichdr;
struct xfs_attr_leaf_entry *entry;
struct xfs_attr_leaf_name_remote *name_rmt;
struct xfs_attr_inactive_list *list;
struct xfs_attr_inactive_list *lp;
int error;
int count;
int size;
int tmp;
int i;
struct xfs_mount *mp = bp->b_target->bt_mount;
leaf = bp->b_addr;
xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &ichdr, leaf);
/*
* Count the number of "remote" value extents.
*/
count = 0;
entry = xfs_attr3_leaf_entryp(leaf);
for (i = 0; i < ichdr.count; entry++, i++) {
if (be16_to_cpu(entry->nameidx) &&
((entry->flags & XFS_ATTR_LOCAL) == 0)) {
name_rmt = xfs_attr3_leaf_name_remote(leaf, i);
if (name_rmt->valueblk)
count++;
}
}
/*
* If there are no "remote" values, we're done.
*/
if (count == 0) {
xfs_trans_brelse(*trans, bp);
return 0;
}
/*
* Allocate storage for a list of all the "remote" value extents.
*/
size = count * sizeof(xfs_attr_inactive_list_t);
list = kmem_alloc(size, KM_SLEEP);
/*
* Identify each of the "remote" value extents.
*/
lp = list;
entry = xfs_attr3_leaf_entryp(leaf);
for (i = 0; i < ichdr.count; entry++, i++) {
if (be16_to_cpu(entry->nameidx) &&
((entry->flags & XFS_ATTR_LOCAL) == 0)) {
name_rmt = xfs_attr3_leaf_name_remote(leaf, i);
if (name_rmt->valueblk) {
lp->valueblk = be32_to_cpu(name_rmt->valueblk);
lp->valuelen = xfs_attr3_rmt_blocks(dp->i_mount,
be32_to_cpu(name_rmt->valuelen));
lp++;
}
}
}
xfs_trans_brelse(*trans, bp); /* unlock for trans. in freextent() */
/*
* Invalidate each of the "remote" value extents.
*/
error = 0;
for (lp = list, i = 0; i < count; i++, lp++) {
tmp = xfs_attr3_leaf_freextent(trans, dp,
lp->valueblk, lp->valuelen);
if (error == 0)
error = tmp; /* save only the 1st errno */
}
kmem_free(list);
return error;
}
/*
* Recurse (gasp!) through the attribute nodes until we find leaves.
* We're doing a depth-first traversal in order to invalidate everything.
*/
STATIC int
xfs_attr3_node_inactive(
struct xfs_trans **trans,
struct xfs_inode *dp,
struct xfs_buf *bp,
int level)
{
xfs_da_blkinfo_t *info;
xfs_da_intnode_t *node;
xfs_dablk_t child_fsb;
xfs_daddr_t parent_blkno, child_blkno;
int error, i;
struct xfs_buf *child_bp;
struct xfs_da_node_entry *btree;
struct xfs_da3_icnode_hdr ichdr;
/*
* Since this code is recursive (gasp!) we must protect ourselves.
*/
if (level > XFS_DA_NODE_MAXDEPTH) {
xfs_trans_brelse(*trans, bp); /* no locks for later trans */
return -EIO;
}
node = bp->b_addr;
dp->d_ops->node_hdr_from_disk(&ichdr, node);
parent_blkno = bp->b_bn;
if (!ichdr.count) {
xfs_trans_brelse(*trans, bp);
return 0;
}
btree = dp->d_ops->node_tree_p(node);
child_fsb = be32_to_cpu(btree[0].before);
xfs_trans_brelse(*trans, bp); /* no locks for later trans */
/*
* If this is the node level just above the leaves, simply loop
* over the leaves removing all of them. If this is higher up
* in the tree, recurse downward.
*/
for (i = 0; i < ichdr.count; i++) {
/*
* Read the subsidiary block to see what we have to work with.
* Don't do this in a transaction. This is a depth-first
* traversal of the tree so we may deal with many blocks
* before we come back to this one.
*/
error = xfs_da3_node_read(*trans, dp, child_fsb, -2, &child_bp,
XFS_ATTR_FORK);
if (error)
return error;
if (child_bp) {
/* save for re-read later */
child_blkno = XFS_BUF_ADDR(child_bp);
/*
* Invalidate the subtree, however we have to.
*/
info = child_bp->b_addr;
switch (info->magic) {
case cpu_to_be16(XFS_DA_NODE_MAGIC):
case cpu_to_be16(XFS_DA3_NODE_MAGIC):
error = xfs_attr3_node_inactive(trans, dp,
child_bp, level + 1);
break;
case cpu_to_be16(XFS_ATTR_LEAF_MAGIC):
case cpu_to_be16(XFS_ATTR3_LEAF_MAGIC):
error = xfs_attr3_leaf_inactive(trans, dp,
child_bp);
break;
default:
error = -EIO;
xfs_trans_brelse(*trans, child_bp);
break;
}
if (error)
return error;
/*
* Remove the subsidiary block from the cache
* and from the log.
*/
error = xfs_da_get_buf(*trans, dp, 0, child_blkno,
&child_bp, XFS_ATTR_FORK);
if (error)
return error;
xfs_trans_binval(*trans, child_bp);
}
/*
* If we're not done, re-read the parent to get the next
* child block number.
*/
if (i + 1 < ichdr.count) {
error = xfs_da3_node_read(*trans, dp, 0, parent_blkno,
&bp, XFS_ATTR_FORK);
if (error)
return error;
node = bp->b_addr;
btree = dp->d_ops->node_tree_p(node);
child_fsb = be32_to_cpu(btree[i + 1].before);
xfs_trans_brelse(*trans, bp);
}
/*
* Atomically commit the whole invalidate stuff.
*/
error = xfs_trans_roll_inode(trans, dp);
if (error)
return error;
}
return 0;
}
/*
* Indiscriminately delete the entire attribute fork
*
* Recurse (gasp!) through the attribute nodes until we find leaves.
* We're doing a depth-first traversal in order to invalidate everything.
*/
static int
xfs_attr3_root_inactive(
struct xfs_trans **trans,
struct xfs_inode *dp)
{
struct xfs_da_blkinfo *info;
struct xfs_buf *bp;
xfs_daddr_t blkno;
int error;
/*
* Read block 0 to see what we have to work with.
* We only get here if we have extents, since we remove
* the extents in reverse order the extent containing
* block 0 must still be there.
*/
error = xfs_da3_node_read(*trans, dp, 0, -1, &bp, XFS_ATTR_FORK);
if (error)
return error;
blkno = bp->b_bn;
/*
* Invalidate the tree, even if the "tree" is only a single leaf block.
* This is a depth-first traversal!
*/
info = bp->b_addr;
switch (info->magic) {
case cpu_to_be16(XFS_DA_NODE_MAGIC):
case cpu_to_be16(XFS_DA3_NODE_MAGIC):
error = xfs_attr3_node_inactive(trans, dp, bp, 1);
break;
case cpu_to_be16(XFS_ATTR_LEAF_MAGIC):
case cpu_to_be16(XFS_ATTR3_LEAF_MAGIC):
error = xfs_attr3_leaf_inactive(trans, dp, bp);
break;
default:
error = -EIO;
xfs_trans_brelse(*trans, bp);
break;
}
if (error)
return error;
/*
* Invalidate the incore copy of the root block.
*/
error = xfs_da_get_buf(*trans, dp, 0, blkno, &bp, XFS_ATTR_FORK);
if (error)
return error;
xfs_trans_binval(*trans, bp); /* remove from cache */
/*
* Commit the invalidate and start the next transaction.
*/
error = xfs_trans_roll_inode(trans, dp);
return error;
}
/*
* xfs_attr_inactive kills all traces of an attribute fork on an inode. It
* removes both the on-disk and in-memory inode fork. Note that this also has to
* handle the condition of inodes without attributes but with an attribute fork
* configured, so we can't use xfs_inode_hasattr() here.
*
* The in-memory attribute fork is removed even on error.
*/
int
xfs_attr_inactive(
struct xfs_inode *dp)
{
struct xfs_trans *trans;
struct xfs_mount *mp;
int lock_mode = XFS_ILOCK_SHARED;
int error = 0;
mp = dp->i_mount;
ASSERT(! XFS_NOT_DQATTACHED(mp, dp));
xfs_ilock(dp, lock_mode);
if (!XFS_IFORK_Q(dp))
goto out_destroy_fork;
xfs_iunlock(dp, lock_mode);
lock_mode = 0;
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_attrinval, 0, 0, 0, &trans);
if (error)
goto out_destroy_fork;
lock_mode = XFS_ILOCK_EXCL;
xfs_ilock(dp, lock_mode);
if (!XFS_IFORK_Q(dp))
goto out_cancel;
/*
* No need to make quota reservations here. We expect to release some
* blocks, not allocate, in the common case.
*/
xfs_trans_ijoin(trans, dp, 0);
/*
* Invalidate and truncate the attribute fork extents. Make sure the
* fork actually has attributes as otherwise the invalidation has no
* blocks to read and returns an error. In this case, just do the fork
* removal below.
*/
if (xfs_inode_hasattr(dp) &&
dp->i_d.di_aformat != XFS_DINODE_FMT_LOCAL) {
error = xfs_attr3_root_inactive(&trans, dp);
if (error)
goto out_cancel;
error = xfs_itruncate_extents(&trans, dp, XFS_ATTR_FORK, 0);
if (error)
goto out_cancel;
}
/* Reset the attribute fork - this also destroys the in-core fork */
xfs_attr_fork_remove(dp, trans);
error = xfs_trans_commit(trans);
xfs_iunlock(dp, lock_mode);
return error;
out_cancel:
xfs_trans_cancel(trans);
out_destroy_fork:
/* kill the in-core attr fork before we drop the inode lock */
if (dp->i_afp)
xfs_idestroy_fork(dp, XFS_ATTR_FORK);
if (lock_mode)
xfs_iunlock(dp, lock_mode);
return error;
}