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FAILED: patch "[PATCH] staging: erofs: fix race of initializing xattrs of a inode at" failed to apply to 4.19-stable tree

PATCH [email protected] 1 participant 1 message Mar 7, 2019

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The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 62dc45979f3f8cb0ea67302a93bff686f0c46c5a Mon Sep 17 00:00:00 2001
From: Gao Xiang <[email protected]>
Date: Mon, 18 Feb 2019 15:19:04 +0800
Subject: [PATCH] staging: erofs: fix race of initializing xattrs of a inode at
the same time

In real scenario, there could be several threads accessing xattrs of the same xattr-uninitialized inode, and init_inode_xattrs() almost at the same time.

That's actually an unexpected behavior, this patch closes the race.

Fixes b17500a0fdba ("staging: erofs: introduce xattr & acl support")
Cc <[email protected]> # 4.19+
Reviewed-by Chao Yu <[email protected]>
Signed-off-by Gao Xiang <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
drivers/staging/erofs/internal.h +8 -3
index 3a27c255950b..e3bfde00c7d2 100644
@@ -327,12 +327,17 @@ static inline erofs_off_t iloc(struct erofs_sb_info *sbi, erofs_nid_t nid)
 	return blknr_to_addr(sbi->meta_blkaddr) + (nid << sbi->islotbits);
 }
 
-#define inode_set_inited_xattr(inode)   (EROFS_V(inode)->flags |= 1)
-#define inode_has_inited_xattr(inode)   (EROFS_V(inode)->flags & 1)
+/* atomic flag definitions */
+#define EROFS_V_EA_INITED_BIT	0
+
+/* bitlock definitions (arranged in reverse order) */
+#define EROFS_V_BL_XATTR_BIT	(BITS_PER_LONG - 1)
 
 struct erofs_vnode {
 	erofs_nid_t nid;
-	unsigned int flags;
+
+	/* atomic flags (including bitlocks) */
+	unsigned long flags;
 
 	unsigned char data_mapping_mode;
 	/* inline size in bytes */
drivers/staging/erofs/xattr.c +29 -12

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