disable fast write path (append) for strict mode, reverse update orde…

…r for relaxed mode (fix utsaslab#16)
paulwedeck · Oct 11, 2023 · 63f8656 · 63f8656
1 parent b4017d0
commit 63f8656
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Showing 2 changed files with 8 additions and 10 deletions.
diff --git a/Linux-5.1/fs/winefs/inode.h b/Linux-5.1/fs/winefs/inode.h
@@ -343,17 +343,15 @@ static inline void check_eof_blocks(struct super_block *sb,
 static inline void pmfs_update_time_and_size(struct inode *inode,
 	struct pmfs_inode *pi)
 {
-	__le32 words[2];
+	__le64 words;
 	__le64 new_pi_size = cpu_to_le64(i_size_read(inode));
 
-	/* pi->i_size, pi->i_ctime, and pi->i_mtime need to be atomically updated.
- 	* So use cmpxchg16b here. */
-	words[0] = cpu_to_le32(inode->i_ctime.tv_sec);
-	words[1] = cpu_to_le32(inode->i_mtime.tv_sec);
-	/* TODO: the following function assumes cmpxchg16b instruction writes
- 	* 16 bytes atomically. Confirm if it is really true. */
-	cmpxchg_double_local(&pi->i_size, (u64 *)&pi->i_ctime, pi->i_size,
-		*(u64 *)&pi->i_ctime, new_pi_size, *(u64 *)words);
+	words = cpu_to_le32(inode->i_mtime.tv_sec);
+	words <<= 32;
+	words |= cpu_to_le32(inode->i_ctime.tv_sec);
+	volatile __le64* target = (__le64*) &pi->i_ctime;
+	*target = words;
+	((volatile struct pmfs_inode*)pi)->i_size =  new_pi_size;
 }
 
 int pmfs_init_inode_inuse_list(struct super_block *sb);

diff --git a/Linux-5.1/fs/winefs/xip.c b/Linux-5.1/fs/winefs/xip.c
@@ -715,7 +715,7 @@ ssize_t pmfs_xip_file_write(struct file *filp, const char __user *buf,
 	start_blk = pos >> sb->s_blocksize_bits;
 	end_blk = start_blk + num_blocks - 1;
 
-	if (!(strong_guarantees && pos < i_size_read(inode))) {
+	if (!strong_guarantees) {
 		num_blocks_found = pmfs_find_data_blocks(inode, start_blk, &block, 1);
 
 		/* Referring to the inode's block size, not 4K */