[PATCH RFC V2 1/1] ocfs2: reserve space for inline xattr before attaching reflink tree

[Gautham Ananthakrishna]

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.

Fixes: ef962df057aa ("ocfs2: xattr: fix inlined xattr reflink")
Cc: stable@xxxxxxxxxxxxxxx

Signed-off-by: Gautham Ananthakrishna <gautham.ananthakrishna@xxxxxxxxxx>
---
 fs/ocfs2/refcounttree.c | 26 ++++++++++++++++++++++++--
 fs/ocfs2/xattr.c        | 11 +----------
 2 files changed, 25 insertions(+), 12 deletions(-)

diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index 3f80a56d0d60..1d427da06bee 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>
@@ -4155,8 +4156,9 @@ static int __ocfs2_reflink(struct dentry *old_dentry,
 	int ret;
 	struct inode *inode = d_inode(old_dentry);
 	struct buffer_head *new_bh = NULL;
+	struct ocfs2_inode_info *oi = OCFS2_I(inode);
 
-	if (OCFS2_I(inode)->ip_flags & OCFS2_INODE_SYSTEM_FILE) {
+	if (oi->ip_flags & OCFS2_INODE_SYSTEM_FILE) {
 		ret = -EINVAL;
 		mlog_errno(ret);
 		goto out;
@@ -4182,6 +4184,26 @@ static int __ocfs2_reflink(struct dentry *old_dentry,
 		goto out_unlock;
 	}
 
+	if ((oi->ip_dyn_features & OCFS2_HAS_XATTR_FL) &&
+	    (oi->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().
+		 */
+		struct ocfs2_inode_info *ni = OCFS2_I(new_inode);
+
+		if (!(ni->ip_dyn_features & OCFS2_INLINE_DATA_FL) &&
+		    !(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);
+
+			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) {
@@ -4189,7 +4211,7 @@ static int __ocfs2_reflink(struct dentry *old_dentry,
 		goto inode_unlock;
 	}
 
-	if (OCFS2_I(inode)->ip_dyn_features & OCFS2_HAS_XATTR_FL) {
+	if (oi->ip_dyn_features & OCFS2_HAS_XATTR_FL) {
 		ret = ocfs2_reflink_xattrs(inode, old_bh,
 					   new_inode, new_bh,
 					   preserve);
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);
-- 
2.39.3