linux/fs/xfs/libxfs/xfs_inode_fork.c

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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2000-2006 Silicon Graphics, Inc.
* All Rights Reserved.
*/
#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_mount.h"
#include "xfs_inode.h"
#include "xfs_trans.h"
#include "xfs_inode_item.h"
#include "xfs_btree.h"
#include "xfs_bmap_btree.h"
#include "xfs_bmap.h"
#include "xfs_error.h"
#include "xfs_trace.h"
#include "xfs_da_format.h"
#include "xfs_da_btree.h"
#include "xfs_dir2_priv.h"
#include "xfs_attr_leaf.h"
kmem_zone_t *xfs_ifork_zone;
void
xfs_init_local_fork(
struct xfs_inode *ip,
int whichfork,
const void *data,
xfs: fix inode fork extent count overflow [commit message is verbose for discussion purposes - will trim it down later. Some questions about implementation details at the end.] Zorro Lang recently ran a new test to stress single inode extent counts now that they are no longer limited by memory allocation. The test was simply: # xfs_io -f -c "falloc 0 40t" /mnt/scratch/big-file # ~/src/xfstests-dev/punch-alternating /mnt/scratch/big-file This test uncovered a problem where the hole punching operation appeared to finish with no error, but apparently only created 268M extents instead of the 10 billion it was supposed to. Further, trying to punch out extents that should have been present resulted in success, but no change in the extent count. It looked like a silent failure. While running the test and observing the behaviour in real time, I observed the extent coutn growing at ~2M extents/minute, and saw this after about an hour: # xfs_io -f -c "stat" /mnt/scratch/big-file |grep next ; \ > sleep 60 ; \ > xfs_io -f -c "stat" /mnt/scratch/big-file |grep next fsxattr.nextents = 127657993 fsxattr.nextents = 129683339 # And a few minutes later this: # xfs_io -f -c "stat" /mnt/scratch/big-file |grep next fsxattr.nextents = 4177861124 # Ah, what? Where did that 4 billion extra extents suddenly come from? Stop the workload, unmount, mount: # xfs_io -f -c "stat" /mnt/scratch/big-file |grep next fsxattr.nextents = 166044375 # And it's back at the expected number. i.e. the extent count is correct on disk, but it's screwed up in memory. I loaded up the extent list, and immediately: # xfs_io -f -c "stat" /mnt/scratch/big-file |grep next fsxattr.nextents = 4192576215 # It's bad again. So, where does that number come from? xfs_fill_fsxattr(): if (ip->i_df.if_flags & XFS_IFEXTENTS) fa->fsx_nextents = xfs_iext_count(&ip->i_df); else fa->fsx_nextents = ip->i_d.di_nextents; And that's the behaviour I just saw in a nutshell. The on disk count is correct, but once the tree is loaded into memory, it goes whacky. Clearly there's something wrong with xfs_iext_count(): inline xfs_extnum_t xfs_iext_count(struct xfs_ifork *ifp) { return ifp->if_bytes / sizeof(struct xfs_iext_rec); } Simple enough, but 134M extents is 2**27, and that's right about where things went wrong. A struct xfs_iext_rec is 16 bytes in size, which means 2**27 * 2**4 = 2**31 and we're right on target for an integer overflow. And, sure enough: struct xfs_ifork { int if_bytes; /* bytes in if_u1 */ .... Once we get 2**27 extents in a file, we overflow if_bytes and the in-core extent count goes wrong. And when we reach 2**28 extents, if_bytes wraps back to zero and things really start to go wrong there. This is where the silent failure comes from - only the first 2**28 extents can be looked up directly due to the overflow, all the extents above this index wrap back to somewhere in the first 2**28 extents. Hence with a regular pattern, trying to punch a hole in the range that didn't have holes mapped to a hole in the first 2**28 extents and so "succeeded" without changing anything. Hence "silent failure"... Fix this by converting if_bytes to a int64_t and converting all the index variables and size calculations to use int64_t types to avoid overflows in future. Signed integers are still used to enable easy detection of extent count underflows. This enables scalability of extent counts to the limits of the on-disk format - MAXEXTNUM (2**31) extents. Current testing is at over 500M extents and still going: fsxattr.nextents = 517310478 Reported-by: Zorro Lang <zlang@redhat.com> Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2019-10-18 04:40:33 +08:00
int64_t size)
{
struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, whichfork);
int mem_size = size, real_size = 0;
bool zero_terminate;
/*
* If we are using the local fork to store a symlink body we need to
* zero-terminate it so that we can pass it back to the VFS directly.
* Overallocate the in-memory fork by one for that and add a zero
* to terminate it below.
*/
zero_terminate = S_ISLNK(VFS_I(ip)->i_mode);
if (zero_terminate)
mem_size++;
if (size) {
real_size = roundup(mem_size, 4);
ifp->if_u1.if_data = kmem_alloc(real_size, KM_NOFS);
memcpy(ifp->if_u1.if_data, data, size);
if (zero_terminate)
ifp->if_u1.if_data[size] = '\0';
} else {
ifp->if_u1.if_data = NULL;
}
ifp->if_bytes = size;
ifp->if_flags &= ~(XFS_IFEXTENTS | XFS_IFBROOT);
ifp->if_flags |= XFS_IFINLINE;
}
/*
* The file is in-lined in the on-disk inode.
*/
STATIC int
xfs_iformat_local(
xfs_inode_t *ip,
xfs_dinode_t *dip,
int whichfork,
int size)
{
/*
* If the size is unreasonable, then something
* is wrong and we just bail out rather than crash in
* kmem_alloc() or memcpy() below.
*/
if (unlikely(size > XFS_DFORK_SIZE(dip, ip->i_mount, whichfork))) {
xfs_warn(ip->i_mount,
"corrupt inode %Lu (bad size %d for local fork, size = %zd).",
(unsigned long long) ip->i_ino, size,
XFS_DFORK_SIZE(dip, ip->i_mount, whichfork));
xfs_inode_verifier_error(ip, -EFSCORRUPTED,
"xfs_iformat_local", dip, sizeof(*dip),
__this_address);
return -EFSCORRUPTED;
}
xfs_init_local_fork(ip, whichfork, XFS_DFORK_PTR(dip, whichfork), size);
return 0;
}
/*
* The file consists of a set of extents all of which fit into the on-disk
* inode.
*/
STATIC int
xfs_iformat_extents(
struct xfs_inode *ip,
struct xfs_dinode *dip,
int whichfork)
{
struct xfs_mount *mp = ip->i_mount;
struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, whichfork);
int state = xfs_bmap_fork_to_state(whichfork);
int nex = XFS_DFORK_NEXTENTS(dip, whichfork);
int size = nex * sizeof(xfs_bmbt_rec_t);
struct xfs_iext_cursor icur;
struct xfs_bmbt_rec *dp;
xfs: use a b+tree for the in-core extent list Replace the current linear list and the indirection array for the in-core extent list with a b+tree to avoid the need for larger memory allocations for the indirection array when lots of extents are present. The current extent list implementations leads to heavy pressure on the memory allocator when modifying files with a high extent count, and can lead to high latencies because of that. The replacement is a b+tree with a few quirks. The leaf nodes directly store the extent record in two u64 values. The encoding is a little bit different from the existing in-core extent records so that the start offset and length which are required for lookups can be retreived with simple mask operations. The inner nodes store a 64-bit key containing the start offset in the first half of the node, and the pointers to the next lower level in the second half. In either case we walk the node from the beginninig to the end and do a linear search, as that is more efficient for the low number of cache lines touched during a search (2 for the inner nodes, 4 for the leaf nodes) than a binary search. We store termination markers (zero length for the leaf nodes, an otherwise impossible high bit for the inner nodes) to terminate the key list / records instead of storing a count to use the available cache lines as efficiently as possible. One quirk of the algorithm is that while we normally split a node half and half like usual btree implementations we just spill over entries added at the very end of the list to a new node on its own. This means we get a 100% fill grade for the common cases of bulk insertion when reading an inode into memory, and when only sequentially appending to a file. The downside is a slightly higher chance of splits on the first random insertions. Both insert and removal manually recurse into the lower levels, but the bulk deletion of the whole tree is still implemented as a recursive function call, although one limited by the overall depth and with very little stack usage in every iteration. For the first few extents we dynamically grow the list from a single extent to the next powers of two until we have a first full leaf block and that building the actual tree. The code started out based on the generic lib/btree.c code from Joern Engel based on earlier work from Peter Zijlstra, but has since been rewritten beyond recognition. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2017-11-04 01:34:46 +08:00
struct xfs_bmbt_irec new;
int i;
/*
* If the number of extents is unreasonable, then something is wrong and
* we just bail out rather than crash in kmem_alloc() or memcpy() below.
*/
if (unlikely(size < 0 || size > XFS_DFORK_SIZE(dip, mp, whichfork))) {
xfs_warn(ip->i_mount, "corrupt inode %Lu ((a)extents = %d).",
(unsigned long long) ip->i_ino, nex);
xfs_inode_verifier_error(ip, -EFSCORRUPTED,
"xfs_iformat_extents(1)", dip, sizeof(*dip),
__this_address);
return -EFSCORRUPTED;
}
xfs: use a b+tree for the in-core extent list Replace the current linear list and the indirection array for the in-core extent list with a b+tree to avoid the need for larger memory allocations for the indirection array when lots of extents are present. The current extent list implementations leads to heavy pressure on the memory allocator when modifying files with a high extent count, and can lead to high latencies because of that. The replacement is a b+tree with a few quirks. The leaf nodes directly store the extent record in two u64 values. The encoding is a little bit different from the existing in-core extent records so that the start offset and length which are required for lookups can be retreived with simple mask operations. The inner nodes store a 64-bit key containing the start offset in the first half of the node, and the pointers to the next lower level in the second half. In either case we walk the node from the beginninig to the end and do a linear search, as that is more efficient for the low number of cache lines touched during a search (2 for the inner nodes, 4 for the leaf nodes) than a binary search. We store termination markers (zero length for the leaf nodes, an otherwise impossible high bit for the inner nodes) to terminate the key list / records instead of storing a count to use the available cache lines as efficiently as possible. One quirk of the algorithm is that while we normally split a node half and half like usual btree implementations we just spill over entries added at the very end of the list to a new node on its own. This means we get a 100% fill grade for the common cases of bulk insertion when reading an inode into memory, and when only sequentially appending to a file. The downside is a slightly higher chance of splits on the first random insertions. Both insert and removal manually recurse into the lower levels, but the bulk deletion of the whole tree is still implemented as a recursive function call, although one limited by the overall depth and with very little stack usage in every iteration. For the first few extents we dynamically grow the list from a single extent to the next powers of two until we have a first full leaf block and that building the actual tree. The code started out based on the generic lib/btree.c code from Joern Engel based on earlier work from Peter Zijlstra, but has since been rewritten beyond recognition. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2017-11-04 01:34:46 +08:00
ifp->if_bytes = 0;
ifp->if_u1.if_root = NULL;
ifp->if_height = 0;
if (size) {
dp = (xfs_bmbt_rec_t *) XFS_DFORK_PTR(dip, whichfork);
xfs_iext_first(ifp, &icur);
for (i = 0; i < nex; i++, dp++) {
xfs_failaddr_t fa;
xfs_bmbt_disk_get_all(dp, &new);
fa = xfs_bmap_validate_extent(ip, whichfork, &new);
if (fa) {
xfs_inode_verifier_error(ip, -EFSCORRUPTED,
"xfs_iformat_extents(2)",
dp, sizeof(*dp), fa);
return -EFSCORRUPTED;
}
xfs_iext_insert(ip, &icur, &new, state);
trace_xfs_read_extent(ip, &icur, state, _THIS_IP_);
xfs_iext_next(ifp, &icur);
}
}
ifp->if_flags |= XFS_IFEXTENTS;
return 0;
}
/*
* The file has too many extents to fit into
* the inode, so they are in B-tree format.
* Allocate a buffer for the root of the B-tree
* and copy the root into it. The i_extents
* field will remain NULL until all of the
* extents are read in (when they are needed).
*/
STATIC int
xfs_iformat_btree(
xfs_inode_t *ip,
xfs_dinode_t *dip,
int whichfork)
{
struct xfs_mount *mp = ip->i_mount;
xfs_bmdr_block_t *dfp;
struct xfs_ifork *ifp;
/* REFERENCED */
int nrecs;
int size;
int level;
ifp = XFS_IFORK_PTR(ip, whichfork);
dfp = (xfs_bmdr_block_t *)XFS_DFORK_PTR(dip, whichfork);
size = XFS_BMAP_BROOT_SPACE(mp, dfp);
nrecs = be16_to_cpu(dfp->bb_numrecs);
level = be16_to_cpu(dfp->bb_level);
/*
* blow out if -- fork has less extents than can fit in
* fork (fork shouldn't be a btree format), root btree
* block has more records than can fit into the fork,
* or the number of extents is greater than the number of
* blocks.
*/
if (unlikely(ifp->if_nextents <= XFS_IFORK_MAXEXT(ip, whichfork) ||
nrecs == 0 ||
XFS_BMDR_SPACE_CALC(nrecs) >
XFS_DFORK_SIZE(dip, mp, whichfork) ||
ifp->if_nextents > ip->i_d.di_nblocks) ||
level == 0 || level > XFS_BTREE_MAXLEVELS) {
xfs_warn(mp, "corrupt inode %Lu (btree).",
(unsigned long long) ip->i_ino);
xfs_inode_verifier_error(ip, -EFSCORRUPTED,
"xfs_iformat_btree", dfp, size,
__this_address);
return -EFSCORRUPTED;
}
ifp->if_broot_bytes = size;
ifp->if_broot = kmem_alloc(size, KM_NOFS);
ASSERT(ifp->if_broot != NULL);
/*
* Copy and convert from the on-disk structure
* to the in-memory structure.
*/
xfs_bmdr_to_bmbt(ip, dfp, XFS_DFORK_SIZE(dip, ip->i_mount, whichfork),
ifp->if_broot, size);
ifp->if_flags &= ~XFS_IFEXTENTS;
ifp->if_flags |= XFS_IFBROOT;
xfs: use a b+tree for the in-core extent list Replace the current linear list and the indirection array for the in-core extent list with a b+tree to avoid the need for larger memory allocations for the indirection array when lots of extents are present. The current extent list implementations leads to heavy pressure on the memory allocator when modifying files with a high extent count, and can lead to high latencies because of that. The replacement is a b+tree with a few quirks. The leaf nodes directly store the extent record in two u64 values. The encoding is a little bit different from the existing in-core extent records so that the start offset and length which are required for lookups can be retreived with simple mask operations. The inner nodes store a 64-bit key containing the start offset in the first half of the node, and the pointers to the next lower level in the second half. In either case we walk the node from the beginninig to the end and do a linear search, as that is more efficient for the low number of cache lines touched during a search (2 for the inner nodes, 4 for the leaf nodes) than a binary search. We store termination markers (zero length for the leaf nodes, an otherwise impossible high bit for the inner nodes) to terminate the key list / records instead of storing a count to use the available cache lines as efficiently as possible. One quirk of the algorithm is that while we normally split a node half and half like usual btree implementations we just spill over entries added at the very end of the list to a new node on its own. This means we get a 100% fill grade for the common cases of bulk insertion when reading an inode into memory, and when only sequentially appending to a file. The downside is a slightly higher chance of splits on the first random insertions. Both insert and removal manually recurse into the lower levels, but the bulk deletion of the whole tree is still implemented as a recursive function call, although one limited by the overall depth and with very little stack usage in every iteration. For the first few extents we dynamically grow the list from a single extent to the next powers of two until we have a first full leaf block and that building the actual tree. The code started out based on the generic lib/btree.c code from Joern Engel based on earlier work from Peter Zijlstra, but has since been rewritten beyond recognition. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2017-11-04 01:34:46 +08:00
ifp->if_bytes = 0;
ifp->if_u1.if_root = NULL;
ifp->if_height = 0;
return 0;
}
int
xfs_iformat_data_fork(
struct xfs_inode *ip,
struct xfs_dinode *dip)
{
struct inode *inode = VFS_I(ip);
int error;
/*
* Initialize the extent count early, as the per-format routines may
* depend on it.
*/
ip->i_df.if_format = dip->di_format;
ip->i_df.if_nextents = be32_to_cpu(dip->di_nextents);
switch (inode->i_mode & S_IFMT) {
case S_IFIFO:
case S_IFCHR:
case S_IFBLK:
case S_IFSOCK:
ip->i_d.di_size = 0;
inode->i_rdev = xfs_to_linux_dev_t(xfs_dinode_get_rdev(dip));
return 0;
case S_IFREG:
case S_IFLNK:
case S_IFDIR:
switch (ip->i_df.if_format) {
case XFS_DINODE_FMT_LOCAL:
error = xfs_iformat_local(ip, dip, XFS_DATA_FORK,
be64_to_cpu(dip->di_size));
if (!error)
error = xfs_ifork_verify_local_data(ip);
return error;
case XFS_DINODE_FMT_EXTENTS:
return xfs_iformat_extents(ip, dip, XFS_DATA_FORK);
case XFS_DINODE_FMT_BTREE:
return xfs_iformat_btree(ip, dip, XFS_DATA_FORK);
default:
xfs_inode_verifier_error(ip, -EFSCORRUPTED, __func__,
dip, sizeof(*dip), __this_address);
return -EFSCORRUPTED;
}
break;
default:
xfs_inode_verifier_error(ip, -EFSCORRUPTED, __func__, dip,
sizeof(*dip), __this_address);
return -EFSCORRUPTED;
}
}
static uint16_t
xfs_dfork_attr_shortform_size(
struct xfs_dinode *dip)
{
struct xfs_attr_shortform *atp =
(struct xfs_attr_shortform *)XFS_DFORK_APTR(dip);
return be16_to_cpu(atp->hdr.totsize);
}
int
xfs_iformat_attr_fork(
struct xfs_inode *ip,
struct xfs_dinode *dip)
{
int error = 0;
/*
* Initialize the extent count early, as the per-format routines may
* depend on it.
*/
ip->i_afp = kmem_cache_zalloc(xfs_ifork_zone, GFP_NOFS | __GFP_NOFAIL);
ip->i_afp->if_format = dip->di_aformat;
if (unlikely(ip->i_afp->if_format == 0)) /* pre IRIX 6.2 file system */
ip->i_afp->if_format = XFS_DINODE_FMT_EXTENTS;
ip->i_afp->if_nextents = be16_to_cpu(dip->di_anextents);
switch (ip->i_afp->if_format) {
case XFS_DINODE_FMT_LOCAL:
error = xfs_iformat_local(ip, dip, XFS_ATTR_FORK,
xfs_dfork_attr_shortform_size(dip));
if (!error)
error = xfs_ifork_verify_local_attr(ip);
break;
case XFS_DINODE_FMT_EXTENTS:
error = xfs_iformat_extents(ip, dip, XFS_ATTR_FORK);
break;
case XFS_DINODE_FMT_BTREE:
error = xfs_iformat_btree(ip, dip, XFS_ATTR_FORK);
break;
default:
xfs_inode_verifier_error(ip, error, __func__, dip,
sizeof(*dip), __this_address);
error = -EFSCORRUPTED;
break;
}
if (error) {
kmem_cache_free(xfs_ifork_zone, ip->i_afp);
ip->i_afp = NULL;
}
return error;
}
/*
* Reallocate the space for if_broot based on the number of records
* being added or deleted as indicated in rec_diff. Move the records
* and pointers in if_broot to fit the new size. When shrinking this
* will eliminate holes between the records and pointers created by
* the caller. When growing this will create holes to be filled in
* by the caller.
*
* The caller must not request to add more records than would fit in
* the on-disk inode root. If the if_broot is currently NULL, then
* if we are adding records, one will be allocated. The caller must also
* not request that the number of records go below zero, although
* it can go to zero.
*
* ip -- the inode whose if_broot area is changing
* ext_diff -- the change in the number of records, positive or negative,
* requested for the if_broot array.
*/
void
xfs_iroot_realloc(
xfs_inode_t *ip,
int rec_diff,
int whichfork)
{
struct xfs_mount *mp = ip->i_mount;
int cur_max;
struct xfs_ifork *ifp;
struct xfs_btree_block *new_broot;
int new_max;
size_t new_size;
char *np;
char *op;
/*
* Handle the degenerate case quietly.
*/
if (rec_diff == 0) {
return;
}
ifp = XFS_IFORK_PTR(ip, whichfork);
if (rec_diff > 0) {
/*
* If there wasn't any memory allocated before, just
* allocate it now and get out.
*/
if (ifp->if_broot_bytes == 0) {
new_size = XFS_BMAP_BROOT_SPACE_CALC(mp, rec_diff);
ifp->if_broot = kmem_alloc(new_size, KM_NOFS);
ifp->if_broot_bytes = (int)new_size;
return;
}
/*
* If there is already an existing if_broot, then we need
* to realloc() it and shift the pointers to their new
* location. The records don't change location because
* they are kept butted up against the btree block header.
*/
cur_max = xfs_bmbt_maxrecs(mp, ifp->if_broot_bytes, 0);
new_max = cur_max + rec_diff;
new_size = XFS_BMAP_BROOT_SPACE_CALC(mp, new_max);
ifp->if_broot = krealloc(ifp->if_broot, new_size,
GFP_NOFS | __GFP_NOFAIL);
op = (char *)XFS_BMAP_BROOT_PTR_ADDR(mp, ifp->if_broot, 1,
ifp->if_broot_bytes);
np = (char *)XFS_BMAP_BROOT_PTR_ADDR(mp, ifp->if_broot, 1,
(int)new_size);
ifp->if_broot_bytes = (int)new_size;
ASSERT(XFS_BMAP_BMDR_SPACE(ifp->if_broot) <=
XFS_IFORK_SIZE(ip, whichfork));
memmove(np, op, cur_max * (uint)sizeof(xfs_fsblock_t));
return;
}
/*
* rec_diff is less than 0. In this case, we are shrinking the
* if_broot buffer. It must already exist. If we go to zero
* records, just get rid of the root and clear the status bit.
*/
ASSERT((ifp->if_broot != NULL) && (ifp->if_broot_bytes > 0));
cur_max = xfs_bmbt_maxrecs(mp, ifp->if_broot_bytes, 0);
new_max = cur_max + rec_diff;
ASSERT(new_max >= 0);
if (new_max > 0)
new_size = XFS_BMAP_BROOT_SPACE_CALC(mp, new_max);
else
new_size = 0;
if (new_size > 0) {
new_broot = kmem_alloc(new_size, KM_NOFS);
/*
* First copy over the btree block header.
*/
memcpy(new_broot, ifp->if_broot,
XFS_BMBT_BLOCK_LEN(ip->i_mount));
} else {
new_broot = NULL;
ifp->if_flags &= ~XFS_IFBROOT;
}
/*
* Only copy the records and pointers if there are any.
*/
if (new_max > 0) {
/*
* First copy the records.
*/
op = (char *)XFS_BMBT_REC_ADDR(mp, ifp->if_broot, 1);
np = (char *)XFS_BMBT_REC_ADDR(mp, new_broot, 1);
memcpy(np, op, new_max * (uint)sizeof(xfs_bmbt_rec_t));
/*
* Then copy the pointers.
*/
op = (char *)XFS_BMAP_BROOT_PTR_ADDR(mp, ifp->if_broot, 1,
ifp->if_broot_bytes);
np = (char *)XFS_BMAP_BROOT_PTR_ADDR(mp, new_broot, 1,
(int)new_size);
memcpy(np, op, new_max * (uint)sizeof(xfs_fsblock_t));
}
kmem_free(ifp->if_broot);
ifp->if_broot = new_broot;
ifp->if_broot_bytes = (int)new_size;
if (ifp->if_broot)
ASSERT(XFS_BMAP_BMDR_SPACE(ifp->if_broot) <=
XFS_IFORK_SIZE(ip, whichfork));
return;
}
/*
* This is called when the amount of space needed for if_data
* is increased or decreased. The change in size is indicated by
* the number of bytes that need to be added or deleted in the
* byte_diff parameter.
*
* If the amount of space needed has decreased below the size of the
* inline buffer, then switch to using the inline buffer. Otherwise,
* use kmem_realloc() or kmem_alloc() to adjust the size of the buffer
* to what is needed.
*
* ip -- the inode whose if_data area is changing
* byte_diff -- the change in the number of bytes, positive or negative,
* requested for the if_data array.
*/
void
xfs_idata_realloc(
struct xfs_inode *ip,
xfs: fix inode fork extent count overflow [commit message is verbose for discussion purposes - will trim it down later. Some questions about implementation details at the end.] Zorro Lang recently ran a new test to stress single inode extent counts now that they are no longer limited by memory allocation. The test was simply: # xfs_io -f -c "falloc 0 40t" /mnt/scratch/big-file # ~/src/xfstests-dev/punch-alternating /mnt/scratch/big-file This test uncovered a problem where the hole punching operation appeared to finish with no error, but apparently only created 268M extents instead of the 10 billion it was supposed to. Further, trying to punch out extents that should have been present resulted in success, but no change in the extent count. It looked like a silent failure. While running the test and observing the behaviour in real time, I observed the extent coutn growing at ~2M extents/minute, and saw this after about an hour: # xfs_io -f -c "stat" /mnt/scratch/big-file |grep next ; \ > sleep 60 ; \ > xfs_io -f -c "stat" /mnt/scratch/big-file |grep next fsxattr.nextents = 127657993 fsxattr.nextents = 129683339 # And a few minutes later this: # xfs_io -f -c "stat" /mnt/scratch/big-file |grep next fsxattr.nextents = 4177861124 # Ah, what? Where did that 4 billion extra extents suddenly come from? Stop the workload, unmount, mount: # xfs_io -f -c "stat" /mnt/scratch/big-file |grep next fsxattr.nextents = 166044375 # And it's back at the expected number. i.e. the extent count is correct on disk, but it's screwed up in memory. I loaded up the extent list, and immediately: # xfs_io -f -c "stat" /mnt/scratch/big-file |grep next fsxattr.nextents = 4192576215 # It's bad again. So, where does that number come from? xfs_fill_fsxattr(): if (ip->i_df.if_flags & XFS_IFEXTENTS) fa->fsx_nextents = xfs_iext_count(&ip->i_df); else fa->fsx_nextents = ip->i_d.di_nextents; And that's the behaviour I just saw in a nutshell. The on disk count is correct, but once the tree is loaded into memory, it goes whacky. Clearly there's something wrong with xfs_iext_count(): inline xfs_extnum_t xfs_iext_count(struct xfs_ifork *ifp) { return ifp->if_bytes / sizeof(struct xfs_iext_rec); } Simple enough, but 134M extents is 2**27, and that's right about where things went wrong. A struct xfs_iext_rec is 16 bytes in size, which means 2**27 * 2**4 = 2**31 and we're right on target for an integer overflow. And, sure enough: struct xfs_ifork { int if_bytes; /* bytes in if_u1 */ .... Once we get 2**27 extents in a file, we overflow if_bytes and the in-core extent count goes wrong. And when we reach 2**28 extents, if_bytes wraps back to zero and things really start to go wrong there. This is where the silent failure comes from - only the first 2**28 extents can be looked up directly due to the overflow, all the extents above this index wrap back to somewhere in the first 2**28 extents. Hence with a regular pattern, trying to punch a hole in the range that didn't have holes mapped to a hole in the first 2**28 extents and so "succeeded" without changing anything. Hence "silent failure"... Fix this by converting if_bytes to a int64_t and converting all the index variables and size calculations to use int64_t types to avoid overflows in future. Signed integers are still used to enable easy detection of extent count underflows. This enables scalability of extent counts to the limits of the on-disk format - MAXEXTNUM (2**31) extents. Current testing is at over 500M extents and still going: fsxattr.nextents = 517310478 Reported-by: Zorro Lang <zlang@redhat.com> Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2019-10-18 04:40:33 +08:00
int64_t byte_diff,
int whichfork)
{
struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, whichfork);
xfs: fix inode fork extent count overflow [commit message is verbose for discussion purposes - will trim it down later. Some questions about implementation details at the end.] Zorro Lang recently ran a new test to stress single inode extent counts now that they are no longer limited by memory allocation. The test was simply: # xfs_io -f -c "falloc 0 40t" /mnt/scratch/big-file # ~/src/xfstests-dev/punch-alternating /mnt/scratch/big-file This test uncovered a problem where the hole punching operation appeared to finish with no error, but apparently only created 268M extents instead of the 10 billion it was supposed to. Further, trying to punch out extents that should have been present resulted in success, but no change in the extent count. It looked like a silent failure. While running the test and observing the behaviour in real time, I observed the extent coutn growing at ~2M extents/minute, and saw this after about an hour: # xfs_io -f -c "stat" /mnt/scratch/big-file |grep next ; \ > sleep 60 ; \ > xfs_io -f -c "stat" /mnt/scratch/big-file |grep next fsxattr.nextents = 127657993 fsxattr.nextents = 129683339 # And a few minutes later this: # xfs_io -f -c "stat" /mnt/scratch/big-file |grep next fsxattr.nextents = 4177861124 # Ah, what? Where did that 4 billion extra extents suddenly come from? Stop the workload, unmount, mount: # xfs_io -f -c "stat" /mnt/scratch/big-file |grep next fsxattr.nextents = 166044375 # And it's back at the expected number. i.e. the extent count is correct on disk, but it's screwed up in memory. I loaded up the extent list, and immediately: # xfs_io -f -c "stat" /mnt/scratch/big-file |grep next fsxattr.nextents = 4192576215 # It's bad again. So, where does that number come from? xfs_fill_fsxattr(): if (ip->i_df.if_flags & XFS_IFEXTENTS) fa->fsx_nextents = xfs_iext_count(&ip->i_df); else fa->fsx_nextents = ip->i_d.di_nextents; And that's the behaviour I just saw in a nutshell. The on disk count is correct, but once the tree is loaded into memory, it goes whacky. Clearly there's something wrong with xfs_iext_count(): inline xfs_extnum_t xfs_iext_count(struct xfs_ifork *ifp) { return ifp->if_bytes / sizeof(struct xfs_iext_rec); } Simple enough, but 134M extents is 2**27, and that's right about where things went wrong. A struct xfs_iext_rec is 16 bytes in size, which means 2**27 * 2**4 = 2**31 and we're right on target for an integer overflow. And, sure enough: struct xfs_ifork { int if_bytes; /* bytes in if_u1 */ .... Once we get 2**27 extents in a file, we overflow if_bytes and the in-core extent count goes wrong. And when we reach 2**28 extents, if_bytes wraps back to zero and things really start to go wrong there. This is where the silent failure comes from - only the first 2**28 extents can be looked up directly due to the overflow, all the extents above this index wrap back to somewhere in the first 2**28 extents. Hence with a regular pattern, trying to punch a hole in the range that didn't have holes mapped to a hole in the first 2**28 extents and so "succeeded" without changing anything. Hence "silent failure"... Fix this by converting if_bytes to a int64_t and converting all the index variables and size calculations to use int64_t types to avoid overflows in future. Signed integers are still used to enable easy detection of extent count underflows. This enables scalability of extent counts to the limits of the on-disk format - MAXEXTNUM (2**31) extents. Current testing is at over 500M extents and still going: fsxattr.nextents = 517310478 Reported-by: Zorro Lang <zlang@redhat.com> Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2019-10-18 04:40:33 +08:00
int64_t new_size = ifp->if_bytes + byte_diff;
ASSERT(new_size >= 0);
ASSERT(new_size <= XFS_IFORK_SIZE(ip, whichfork));
if (byte_diff == 0)
return;
if (new_size == 0) {
kmem_free(ifp->if_u1.if_data);
ifp->if_u1.if_data = NULL;
ifp->if_bytes = 0;
return;
}
/*
* For inline data, the underlying buffer must be a multiple of 4 bytes
* in size so that it can be logged and stay on word boundaries.
* We enforce that here.
*/
ifp->if_u1.if_data = krealloc(ifp->if_u1.if_data, roundup(new_size, 4),
GFP_NOFS | __GFP_NOFAIL);
ifp->if_bytes = new_size;
}
void
xfs_idestroy_fork(
struct xfs_ifork *ifp)
{
if (ifp->if_broot != NULL) {
kmem_free(ifp->if_broot);
ifp->if_broot = NULL;
}
/*
* If the format is local, then we can't have an extents array so just
* look for an inline data array. If we're not local then we may or may
* not have an extents list, so check and free it up if we do.
*/
if (ifp->if_format == XFS_DINODE_FMT_LOCAL) {
kmem_free(ifp->if_u1.if_data);
ifp->if_u1.if_data = NULL;
} else if (ifp->if_flags & XFS_IFEXTENTS) {
if (ifp->if_height)
xfs_iext_destroy(ifp);
}
}
/*
* Convert in-core extents to on-disk form
*
* In the case of the data fork, the in-core and on-disk fork sizes can be
* different due to delayed allocation extents. We only copy on-disk extents
* here, so callers must always use the physical fork size to determine the
* size of the buffer passed to this routine. We will return the size actually
* used.
*/
int
xfs_iextents_copy(
struct xfs_inode *ip,
struct xfs_bmbt_rec *dp,
int whichfork)
{
int state = xfs_bmap_fork_to_state(whichfork);
struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, whichfork);
struct xfs_iext_cursor icur;
struct xfs_bmbt_irec rec;
xfs: fix inode fork extent count overflow [commit message is verbose for discussion purposes - will trim it down later. Some questions about implementation details at the end.] Zorro Lang recently ran a new test to stress single inode extent counts now that they are no longer limited by memory allocation. The test was simply: # xfs_io -f -c "falloc 0 40t" /mnt/scratch/big-file # ~/src/xfstests-dev/punch-alternating /mnt/scratch/big-file This test uncovered a problem where the hole punching operation appeared to finish with no error, but apparently only created 268M extents instead of the 10 billion it was supposed to. Further, trying to punch out extents that should have been present resulted in success, but no change in the extent count. It looked like a silent failure. While running the test and observing the behaviour in real time, I observed the extent coutn growing at ~2M extents/minute, and saw this after about an hour: # xfs_io -f -c "stat" /mnt/scratch/big-file |grep next ; \ > sleep 60 ; \ > xfs_io -f -c "stat" /mnt/scratch/big-file |grep next fsxattr.nextents = 127657993 fsxattr.nextents = 129683339 # And a few minutes later this: # xfs_io -f -c "stat" /mnt/scratch/big-file |grep next fsxattr.nextents = 4177861124 # Ah, what? Where did that 4 billion extra extents suddenly come from? Stop the workload, unmount, mount: # xfs_io -f -c "stat" /mnt/scratch/big-file |grep next fsxattr.nextents = 166044375 # And it's back at the expected number. i.e. the extent count is correct on disk, but it's screwed up in memory. I loaded up the extent list, and immediately: # xfs_io -f -c "stat" /mnt/scratch/big-file |grep next fsxattr.nextents = 4192576215 # It's bad again. So, where does that number come from? xfs_fill_fsxattr(): if (ip->i_df.if_flags & XFS_IFEXTENTS) fa->fsx_nextents = xfs_iext_count(&ip->i_df); else fa->fsx_nextents = ip->i_d.di_nextents; And that's the behaviour I just saw in a nutshell. The on disk count is correct, but once the tree is loaded into memory, it goes whacky. Clearly there's something wrong with xfs_iext_count(): inline xfs_extnum_t xfs_iext_count(struct xfs_ifork *ifp) { return ifp->if_bytes / sizeof(struct xfs_iext_rec); } Simple enough, but 134M extents is 2**27, and that's right about where things went wrong. A struct xfs_iext_rec is 16 bytes in size, which means 2**27 * 2**4 = 2**31 and we're right on target for an integer overflow. And, sure enough: struct xfs_ifork { int if_bytes; /* bytes in if_u1 */ .... Once we get 2**27 extents in a file, we overflow if_bytes and the in-core extent count goes wrong. And when we reach 2**28 extents, if_bytes wraps back to zero and things really start to go wrong there. This is where the silent failure comes from - only the first 2**28 extents can be looked up directly due to the overflow, all the extents above this index wrap back to somewhere in the first 2**28 extents. Hence with a regular pattern, trying to punch a hole in the range that didn't have holes mapped to a hole in the first 2**28 extents and so "succeeded" without changing anything. Hence "silent failure"... Fix this by converting if_bytes to a int64_t and converting all the index variables and size calculations to use int64_t types to avoid overflows in future. Signed integers are still used to enable easy detection of extent count underflows. This enables scalability of extent counts to the limits of the on-disk format - MAXEXTNUM (2**31) extents. Current testing is at over 500M extents and still going: fsxattr.nextents = 517310478 Reported-by: Zorro Lang <zlang@redhat.com> Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2019-10-18 04:40:33 +08:00
int64_t copied = 0;
ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED));
ASSERT(ifp->if_bytes > 0);
for_each_xfs_iext(ifp, &icur, &rec) {
if (isnullstartblock(rec.br_startblock))
continue;
ASSERT(xfs_bmap_validate_extent(ip, whichfork, &rec) == NULL);
xfs_bmbt_disk_set_all(dp, &rec);
trace_xfs_write_extent(ip, &icur, state, _RET_IP_);
copied += sizeof(struct xfs_bmbt_rec);
dp++;
}
ASSERT(copied > 0);
ASSERT(copied <= ifp->if_bytes);
return copied;
}
/*
* Each of the following cases stores data into the same region
* of the on-disk inode, so only one of them can be valid at
* any given time. While it is possible to have conflicting formats
* and log flags, e.g. having XFS_ILOG_?DATA set when the fork is
* in EXTENTS format, this can only happen when the fork has
* changed formats after being modified but before being flushed.
* In these cases, the format always takes precedence, because the
* format indicates the current state of the fork.
*/
void
xfs_iflush_fork(
xfs_inode_t *ip,
xfs_dinode_t *dip,
struct xfs_inode_log_item *iip,
int whichfork)
{
char *cp;
struct xfs_ifork *ifp;
xfs_mount_t *mp;
static const short brootflag[2] =
{ XFS_ILOG_DBROOT, XFS_ILOG_ABROOT };
static const short dataflag[2] =
{ XFS_ILOG_DDATA, XFS_ILOG_ADATA };
static const short extflag[2] =
{ XFS_ILOG_DEXT, XFS_ILOG_AEXT };
if (!iip)
return;
ifp = XFS_IFORK_PTR(ip, whichfork);
/*
* This can happen if we gave up in iformat in an error path,
* for the attribute fork.
*/
if (!ifp) {
ASSERT(whichfork == XFS_ATTR_FORK);
return;
}
cp = XFS_DFORK_PTR(dip, whichfork);
mp = ip->i_mount;
switch (ifp->if_format) {
case XFS_DINODE_FMT_LOCAL:
if ((iip->ili_fields & dataflag[whichfork]) &&
(ifp->if_bytes > 0)) {
ASSERT(ifp->if_u1.if_data != NULL);
ASSERT(ifp->if_bytes <= XFS_IFORK_SIZE(ip, whichfork));
memcpy(cp, ifp->if_u1.if_data, ifp->if_bytes);
}
break;
case XFS_DINODE_FMT_EXTENTS:
ASSERT((ifp->if_flags & XFS_IFEXTENTS) ||
!(iip->ili_fields & extflag[whichfork]));
if ((iip->ili_fields & extflag[whichfork]) &&
(ifp->if_bytes > 0)) {
ASSERT(ifp->if_nextents > 0);
(void)xfs_iextents_copy(ip, (xfs_bmbt_rec_t *)cp,
whichfork);
}
break;
case XFS_DINODE_FMT_BTREE:
if ((iip->ili_fields & brootflag[whichfork]) &&
(ifp->if_broot_bytes > 0)) {
ASSERT(ifp->if_broot != NULL);
ASSERT(XFS_BMAP_BMDR_SPACE(ifp->if_broot) <=
XFS_IFORK_SIZE(ip, whichfork));
xfs_bmbt_to_bmdr(mp, ifp->if_broot, ifp->if_broot_bytes,
(xfs_bmdr_block_t *)cp,
XFS_DFORK_SIZE(dip, mp, whichfork));
}
break;
case XFS_DINODE_FMT_DEV:
if (iip->ili_fields & XFS_ILOG_DEV) {
ASSERT(whichfork == XFS_DATA_FORK);
xfs_dinode_put_rdev(dip,
linux_to_xfs_dev_t(VFS_I(ip)->i_rdev));
}
break;
default:
ASSERT(0);
break;
}
}
/* Convert bmap state flags to an inode fork. */
struct xfs_ifork *
xfs_iext_state_to_fork(
struct xfs_inode *ip,
int state)
{
if (state & BMAP_COWFORK)
return ip->i_cowfp;
else if (state & BMAP_ATTRFORK)
return ip->i_afp;
return &ip->i_df;
}
/*
* Initialize an inode's copy-on-write fork.
*/
void
xfs_ifork_init_cow(
struct xfs_inode *ip)
{
if (ip->i_cowfp)
return;
ip->i_cowfp = kmem_cache_zalloc(xfs_ifork_zone,
GFP_NOFS | __GFP_NOFAIL);
ip->i_cowfp->if_flags = XFS_IFEXTENTS;
ip->i_cowfp->if_format = XFS_DINODE_FMT_EXTENTS;
}
/* Verify the inline contents of the data fork of an inode. */
int
xfs_ifork_verify_local_data(
struct xfs_inode *ip)
{
xfs_failaddr_t fa = NULL;
switch (VFS_I(ip)->i_mode & S_IFMT) {
case S_IFDIR:
fa = xfs_dir2_sf_verify(ip);
break;
case S_IFLNK:
fa = xfs_symlink_shortform_verify(ip);
break;
default:
break;
}
if (fa) {
xfs_inode_verifier_error(ip, -EFSCORRUPTED, "data fork",
ip->i_df.if_u1.if_data, ip->i_df.if_bytes, fa);
return -EFSCORRUPTED;
}
return 0;
}
/* Verify the inline contents of the attr fork of an inode. */
int
xfs_ifork_verify_local_attr(
struct xfs_inode *ip)
{
struct xfs_ifork *ifp = ip->i_afp;
xfs_failaddr_t fa;
if (!ifp)
fa = __this_address;
else
fa = xfs_attr_shortform_verify(ip);
if (fa) {
xfs_inode_verifier_error(ip, -EFSCORRUPTED, "attr fork",
ifp ? ifp->if_u1.if_data : NULL,
ifp ? ifp->if_bytes : 0, fa);
return -EFSCORRUPTED;
}
return 0;
}