RE: [PATCH RFC 1/1] ocfs2: reserve space for inline xattr before attaching reflink tree
From: Gautham Ananthakrishna
Date: Wed Sep 11 2024 - 23:02:21 EST
HI Joseph,
Thank you for providing comments. I have addressed them and sent a V1 version for review.
Thanks,
Gautham.
-----Original Message-----
From: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx>
Sent: Wednesday, September 11, 2024 12:58 PM
To: Gautham Ananthakrishna <gautham.ananthakrishna@xxxxxxxxxx>
Cc: Junxiao Bi <junxiao.bi@xxxxxxxxxx>; Rajesh Sivaramasubramaniom <rajesh.sivaramasubramaniom@xxxxxxxxxx>; ocfs2-devel@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
Subject: Re: [PATCH RFC 1/1] ocfs2: reserve space for inline xattr before attaching reflink tree
On 9/10/24 12:40 PM, Gautham Ananthakrishna wrote:
> One of our customers reported a crash and a corrupted ocfs2 filesystem.
> The crash was due to the detection of corruption. Upon
> troubleshooting, the fsck -fn output showed the below corruption
>
> [EXTENT_LIST_FREE] Extent list in owner 33080590 claims 230 as the
> next free chain record, but fsck believes the largest valid value is
> 227. Clamp the next record value? n
>
> The stat output from the debugfs.ocfs2 showed the following corruption
> where the "Next Free Rec:" had overshot the "Count:" in the root
> metadata block.
>
> Inode: 33080590 Mode: 0640 Generation: 2619713622 (0x9c25a856)
> FS Generation: 904309833 (0x35e6ac49)
> CRC32: 00000000 ECC: 0000
> Type: Regular Attr: 0x0 Flags: Valid
> Dynamic Features: (0x16) HasXattr InlineXattr Refcounted
> Extended Attributes Block: 0 Extended Attributes Inline Size: 256
> User: 0 (root) Group: 0 (root) Size: 281320357888
> Links: 1 Clusters: 141738
> ctime: 0x66911b56 0x316edcb8 -- Fri Jul 12 06:02:30.829349048 2024
> atime: 0x66911d6b 0x7f7a28d -- Fri Jul 12 06:11:23.133669517 2024
> mtime: 0x66911b56 0x12ed75d7 -- Fri Jul 12 06:02:30.317552087 2024
> dtime: 0x0 -- Wed Dec 31 17:00:00 1969
> Refcount Block: 2777346
> Last Extblk: 2886943 Orphan Slot: 0
> Sub Alloc Slot: 0 Sub Alloc Bit: 14
> Tree Depth: 1 Count: 227 Next Free Rec: 230
> ## Offset Clusters Block#
> 0 0 2310 2776351
> 1 2310 2139 2777375
> 2 4449 1221 2778399
> 3 5670 731 2779423
> 4 6401 566 2780447
> ....... .... .......
> ....... .... .......
>
> The issue was in the reflink workfow while reserving space for inline xattr.
> The problematic function is ocfs2_reflink_xattr_inline(). By the time
> this function is called the reflink tree is already recreated at the
> destination inode from the source inode. At this point, this function
> reserves space space inline xattrs at the destination inode without
> even checking if there is space at the root metadata block. It simply
> reduces the l_count from 243 to 227 thereby making space of 256 bytes
> for inline xattr whereas the inode already has extents beyond this
> index (in this case upto 230), thereby causing corruption.
>
> The fix for this is to reserve space for inline metadata before the at
> the destination inode before the reflink tree gets recreated. The
> customer has verified the fix.
>
> Signed-off-by: Gautham Ananthakrishna
> <gautham.ananthakrishna@xxxxxxxxxx>
Fixes: ef962df057aa ("ocfs2: xattr: fix inlined xattr reflink")
Cc: <stable@xxxxxxxxxxxxxxx>
> ---
> fs/ocfs2/refcounttree.c | 18 ++++++++++++++++++
> fs/ocfs2/xattr.c | 11 +----------
> 2 files changed, 19 insertions(+), 10 deletions(-)
>
> diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c index
> 3f80a56d0d60..c0edb32a7ff6 100644
> --- a/fs/ocfs2/refcounttree.c
> +++ b/fs/ocfs2/refcounttree.c
> @@ -25,6 +25,7 @@
> #include "namei.h"
> #include "ocfs2_trace.h"
> #include "file.h"
> +#include "symlink.h"
>
> #include <linux/bio.h>
> #include <linux/blkdev.h>
> @@ -4182,6 +4183,23 @@ static int __ocfs2_reflink(struct dentry *old_dentry,
> goto out_unlock;
> }
>
> + if ((OCFS2_I(inode)->ip_dyn_features & OCFS2_HAS_XATTR_FL) &&
^ align it here, please.
> + (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_XATTR_FL)) {
> + /*
> + * Adjust extent record count to reserve space for extended attribute.
> + * Inline data count had been adjusted in ocfs2_duplicate_inline_data().
> + */
> + if (!(OCFS2_I(new_inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL)
> +&&
^ ditto.
And since there are many places access OCFS2_I(new_inode), I'd like define a variable for it. This can also make code in one line much shorter. e.g.
struct ocfs2_inode_info *oi = OCFS2_I(inode);
> + !(ocfs2_inode_is_fast_symlink(new_inode))) {
> + struct ocfs2_dinode *new_di = new_bh->b_data;
> + struct ocfs2_dinode *old_di = old_bh->b_data;
> + struct ocfs2_extent_list *el = &new_di->id2.i_list;
> + int inline_size = le16_to_cpu(old_di->i_xattr_inline_size);
Add a blank line here.
BTW, also cc lkml.
Thanks,
Joseph
> + le16_add_cpu(&el->l_count, -(inline_size /
> + sizeof(struct ocfs2_extent_rec)));
> + }
> + }
> +
> ret = ocfs2_create_reflink_node(inode, old_bh,
> new_inode, new_bh, preserve);
> if (ret) {
> diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c index
> 3b81213ed7b8..a9f716ec89e2 100644
> --- a/fs/ocfs2/xattr.c
> +++ b/fs/ocfs2/xattr.c
> @@ -6511,16 +6511,7 @@ static int ocfs2_reflink_xattr_inline(struct ocfs2_xattr_reflink *args)
> }
>
> new_oi = OCFS2_I(args->new_inode);
> - /*
> - * Adjust extent record count to reserve space for extended attribute.
> - * Inline data count had been adjusted in ocfs2_duplicate_inline_data().
> - */
> - if (!(new_oi->ip_dyn_features & OCFS2_INLINE_DATA_FL) &&
> - !(ocfs2_inode_is_fast_symlink(args->new_inode))) {
> - struct ocfs2_extent_list *el = &new_di->id2.i_list;
> - le16_add_cpu(&el->l_count, -(inline_size /
> - sizeof(struct ocfs2_extent_rec)));
> - }
> +
> spin_lock(&new_oi->ip_lock);
> new_oi->ip_dyn_features |= OCFS2_HAS_XATTR_FL | OCFS2_INLINE_XATTR_FL;
> new_di->i_dyn_features = cpu_to_le16(new_oi->ip_dyn_features);