From mboxrd@z Thu Jan  1 00:00:00 1970
From: Junxiao Bi <junxiao.bi@oracle.com>
Date: Fri, 20 Sep 2019 09:57:25 -0700
Subject: [Ocfs2-devel] [PATCH V2 1/2] ocfs2: protect extent tree in the
 ocfs2_prepare_inode_for_write
In-Reply-To: <1568772175-2906-2-git-send-email-sunny.s.zhang@oracle.com>
References: <1568772175-2906-1-git-send-email-sunny.s.zhang@oracle.com>
	<1568772175-2906-2-git-send-email-sunny.s.zhang@oracle.com>
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To: ocfs2-devel@oss.oracle.com

On 9/17/19 7:02 PM, Shuning Zhang wrote:

> When the extent tree is modified, it should be protected by
> inode cluster lock and ip_alloc_sem.
>
> The extent tree is accessed and modified in the
> ocfs2_prepare_inode_for_write, but isn't protected
> by ip_alloc_sem.
>
> The following is a case. The function ocfs2_fiemap is accessing
> the extent tree, which is modified at the same time.
>
> [47145.974472] kernel BUG at fs/ocfs2/extent_map.c:475!
> [47145.974480] invalid opcode: 0000 [#1] SMP
> [47145.974489] Modules linked in: tun ocfs2 ocfs2_nodemanager configfs
> ocfs2_stackglue xen_netback xen_blkback xen_gntalloc xen_gntdev xen_evtchn
> xenfs xen_privcmd vfat fat bnx2fc fcoe libfcoe libfc scsi_transport_fc sunrpc
> bridge 8021q mrp garp stp llc ib_iser rdma_cm ib_cm iw_cm ib_sa ib_mad
> ib_core ib_addr dm_round_robin dm_multipath sg pcspkr raid1 shpchp
> ipmi_devintf ipmi_msghandler ext4 jbd2 mbcache2 sd_mod nvme nvme_core bnxt_en
> xhci_pci xhci_hcd crc32c_intel be2iscsi bnx2i cnic uio cxgb4i cxgb4 cxgb3i
> libcxgbi ipv6 cxgb3 mdio qla4xxx wmi dm_mirror dm_region_hash dm_log dm_mod
> iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi iscsi_ibft
> iscsi_boot_sysfs
> [47145.974636] CPU: 16 PID: 14047 Comm: o2info Not tainted
> 4.1.12-124.23.1.el6uek.x86_64 #2
> [47145.974646] Hardware name: Oracle Corporation ORACLE SERVER X7-2L/ASM, MB
> MECH, X7-2L, BIOS 42040600 10/19/2018
> [47145.974658] task: ffff88019487e200 ti: ffff88003daa4000 task.ti:
> ffff88003daa4000
> [47145.974667] RIP: e030:[<ffffffffa05e4840>]  [<ffffffffa05e4840>]
> ocfs2_get_clusters_nocache.isra.11+0x390/0x550 [ocfs2]
> [47145.974708] RSP: e02b:ffff88003daa7d88  EFLAGS: 00010287
> [47145.974713] RAX: 00000000000000de RBX: ffff8801d1104030 RCX:
> ffff8801d1104e10
> [47145.974719] RDX: 00000000000000de RSI: 000000000009ec40 RDI:
> ffff8801d1104e24
> [47145.974725] RBP: ffff88003daa7df8 R08: ffff88003daa7e38 R09:
> 0000000000000000
> [47145.974732] R10: 000000000009ec3f R11: 0000000000000246 R12:
> 000000000009ec3f
> [47145.974739] R13: ffff88004c419000 R14: 0000000000000002 R15:
> ffff88003daa7e28
> [47145.974754] FS:  00007fdbccc92720(0000) GS:ffff880358800000(0000)
> knlGS:ffff880358800000
> [47145.974764] CS:  e033 DS: 0000 ES: 0000 CR0: 0000000080050033
> [47145.974772] CR2: 00007fd5dfcd8350 CR3: 0000000208677000 CR4:
> 0000000000042660
> [47145.974785] Stack:
> [47145.974790]  ffff88003daa7df8 00002000a05e249b ffff8801d1104000
> ffff88003daa7e2c
> [47145.974802]  ffff88003daa7e38 ffff88000cc484c0 ffff880145f5b478
> 0000000000000000
> [47145.974811]  0000000000002000 ffff88000cc484c0 ffff88003daa7ea0
> 0000000000000000
> [47145.974820] Call Trace:
> [47145.974837]  [<ffffffffa05e53e3>] ocfs2_fiemap+0x1e3/0x430 [ocfs2]
> [47145.974848]  [<ffffffff816f644f>] ? xen_hypervisor_callback+0x7f/0x120
> [47145.974855]  [<ffffffff816f6448>] ? xen_hypervisor_callback+0x78/0x120
> [47145.974861]  [<ffffffff816f64a3>] ? xen_hypervisor_callback+0xd3/0x120
> [47145.974872]  [<ffffffff81220905>] do_vfs_ioctl+0x155/0x510
> [47145.974878]  [<ffffffff81220d41>] SyS_ioctl+0x81/0xa0
> [47145.974885]  [<ffffffff816f1b9f>] ? system_call_after_swapgs+0xe9/0x190
> [47145.974891]  [<ffffffff816f1b98>] ? system_call_after_swapgs+0xe2/0x190
> [47145.974899]  [<ffffffff816f1b91>] ? system_call_after_swapgs+0xdb/0x190
> [47145.974905]  [<ffffffff816f1c5e>] system_call_fastpath+0x18/0xd8
> [47145.974910] Code: 18 48 c7 c6 60 7f 65 a0 31 c0 bb e2 ff ff ff 48 8b 4a 40
> 48 8b 7a 28 48 c7 c2 78 2d 66 a0 e8 38 4f 05 00 e9 28 fe ff ff 0f 1f 00 <0f>
> 0b 66 0f 1f 44 00 00 bb 86 ff ff ff e9 13 fe ff ff 66 0f 1f
> [47145.975000] RIP  [<ffffffffa05e4840>]
> ocfs2_get_clusters_nocache.isra.11+0x390/0x550 [ocfs2]
> [47145.975018]  RSP <ffff88003daa7d88>
> [47145.989999] ---[ end trace c8aa0c8180e869dc ]---
> [47146.087579] Kernel panic - not syncing: Fatal exception
> [47146.087691] Kernel Offset: disabled
>
> Signed-off-by: Shuning Zhang <sunny.s.zhang@oracle.com>

Looks good.

Reviewed-by: Junxiao Bi <junxiao.bi@oracle.com>

> ---
>   fs/ocfs2/file.c | 129 ++++++++++++++++++++++++++++++++++++++++++++------------
>   1 file changed, 101 insertions(+), 28 deletions(-)
>
> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
> index 4435df3..dff4ab2 100644
> --- a/fs/ocfs2/file.c
> +++ b/fs/ocfs2/file.c
> @@ -2119,27 +2119,90 @@ static int ocfs2_prepare_inode_for_refcount(struct inode *inode,
>   	return ret;
>   }
>   
> +static int ocfs2_inode_lock_for_extent_tree(struct inode *inode,
> +					    struct buffer_head **di_bh,
> +					    int meta_level,
> +					    int overwrite_io,
> +					    int write_sem,
> +					    int wait)
> +{
> +	int ret = 0;
> +
> +	if (wait)
> +		ret = ocfs2_inode_lock(inode, NULL, meta_level);
> +	else
> +		ret = ocfs2_try_inode_lock(inode,
> +			overwrite_io ? NULL : di_bh, meta_level);
> +	if (ret < 0) {
> +		goto out;
> +	}
> +
> +	if (wait) {
> +		if (write_sem)
> +			down_write(&OCFS2_I(inode)->ip_alloc_sem);
> +		else
> +			down_read(&OCFS2_I(inode)->ip_alloc_sem);
> +	} else {
> +		if (write_sem)
> +			ret = down_write_trylock(&OCFS2_I(inode)->ip_alloc_sem);
> +		else
> +			ret = down_read_trylock(&OCFS2_I(inode)->ip_alloc_sem);
> +
> +		if (!ret) {
> +			ret = -EAGAIN;
> +			goto out_unlock;
> +		}
> +	}
> +
> +	return ret;
> +
> +out_unlock:
> +	brelse(*di_bh);
> +	ocfs2_inode_unlock(inode, meta_level);
> +out:
> +	return ret;
> +}
> +
> +static void ocfs2_inode_unlock_for_extent_tree(struct inode *inode,
> +					       struct buffer_head **di_bh,
> +					       int meta_level,
> +					       int write_sem)
> +{
> +	if (write_sem)
> +		up_write(&OCFS2_I(inode)->ip_alloc_sem);
> +	else
> +		up_read(&OCFS2_I(inode)->ip_alloc_sem);
> +
> +	brelse(*di_bh);
> +	*di_bh = NULL;
> +
> +	if (meta_level >= 0)
> +		ocfs2_inode_unlock(inode, meta_level);
> +}
> +
>   static int ocfs2_prepare_inode_for_write(struct file *file,
>   					 loff_t pos, size_t count, int wait)
>   {
> -	int ret = 0, meta_level = 0, overwrite_io = 0;
> +	int ret = 0, meta_level = 0, overwrite_io = 0, write_sem = 0;
>   	struct dentry *dentry = file->f_path.dentry;
>   	struct inode *inode = d_inode(dentry);
>   	struct buffer_head *di_bh = NULL;
>   	loff_t end;
> +	u32 cpos;
> +	u32 clusters;
>   
>   	/*
>   	 * We start with a read level meta lock and only jump to an ex
>   	 * if we need to make modifications here.
>   	 */
>   	for(;;) {
> -		if (wait)
> -			ret = ocfs2_inode_lock(inode, NULL, meta_level);
> -		else
> -			ret = ocfs2_try_inode_lock(inode,
> -				overwrite_io ? NULL : &di_bh, meta_level);
> +		ret = ocfs2_inode_lock_for_extent_tree(inode,
> +						       &di_bh,
> +						       meta_level,
> +						       overwrite_io,
> +						       write_sem,
> +						       wait);
>   		if (ret < 0) {
> -			meta_level = -1;
>   			if (ret != -EAGAIN)
>   				mlog_errno(ret);
>   			goto out;
> @@ -2151,15 +2214,8 @@ static int ocfs2_prepare_inode_for_write(struct file *file,
>   		 */
>   		if (!wait && !overwrite_io) {
>   			overwrite_io = 1;
> -			if (!down_read_trylock(&OCFS2_I(inode)->ip_alloc_sem)) {
> -				ret = -EAGAIN;
> -				goto out_unlock;
> -			}
>   
>   			ret = ocfs2_overwrite_io(inode, di_bh, pos, count);
> -			brelse(di_bh);
> -			di_bh = NULL;
> -			up_read(&OCFS2_I(inode)->ip_alloc_sem);
>   			if (ret < 0) {
>   				if (ret != -EAGAIN)
>   					mlog_errno(ret);
> @@ -2178,7 +2234,10 @@ static int ocfs2_prepare_inode_for_write(struct file *file,
>   		 * set inode->i_size at the end of a write. */
>   		if (should_remove_suid(dentry)) {
>   			if (meta_level == 0) {
> -				ocfs2_inode_unlock(inode, meta_level);
> +				ocfs2_inode_unlock_for_extent_tree(inode,
> +								   &di_bh,
> +								   meta_level,
> +								   write_sem);
>   				meta_level = 1;
>   				continue;
>   			}
> @@ -2194,18 +2253,32 @@ static int ocfs2_prepare_inode_for_write(struct file *file,
>   
>   		ret = ocfs2_check_range_for_refcount(inode, pos, count);
>   		if (ret == 1) {
> -			ocfs2_inode_unlock(inode, meta_level);
> -			meta_level = -1;
> -
> -			ret = ocfs2_prepare_inode_for_refcount(inode,
> -							       file,
> -							       pos,
> -							       count,
> -							       &meta_level);
> +			ocfs2_inode_unlock_for_extent_tree(inode,
> +							   &di_bh,
> +							   meta_level,
> +							   write_sem);
> +			ret = ocfs2_inode_lock_for_extent_tree(inode,
> +							       &di_bh,
> +							       meta_level,
> +							       overwrite_io,
> +							       1,
> +							       wait);
> +			write_sem = 1;
> +			if (ret < 0) {
> +				if (ret != -EAGAIN)
> +					mlog_errno(ret);
> +				goto out;
> +			}
> +
> +			cpos = pos >> OCFS2_SB(inode->i_sb)->s_clustersize_bits;
> +			clusters =
> +				ocfs2_clusters_for_bytes(inode->i_sb, pos + count) - cpos;
> +			ret = ocfs2_refcount_cow(inode, di_bh, cpos, clusters, UINT_MAX);
>   		}
>   
>   		if (ret < 0) {
> -			mlog_errno(ret);
> +			if (ret != -EAGAIN)
> +				mlog_errno(ret);
>   			goto out_unlock;
>   		}
>   
> @@ -2216,10 +2289,10 @@ static int ocfs2_prepare_inode_for_write(struct file *file,
>   	trace_ocfs2_prepare_inode_for_write(OCFS2_I(inode)->ip_blkno,
>   					    pos, count, wait);
>   
> -	brelse(di_bh);
> -
> -	if (meta_level >= 0)
> -		ocfs2_inode_unlock(inode, meta_level);
> +	ocfs2_inode_unlock_for_extent_tree(inode,
> +					   &di_bh,
> +					   meta_level,
> +					   write_sem);
>   
>   out:
>   	return ret;