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Message-ID: <20140527141708.GA2842@mwanda> Date: Tue, 27 May 2014 17:17:08 +0300 From: Dan Carpenter <dan.carpenter@...cle.com> To: Namjae Jeon <namjae.jeon@...sung.com> Cc: linux-ext4@...r.kernel.org Subject: re: ext4: serialize unaligned asynchronous DIO Hello Namjae Jeon, The patch 00532604c72e: "ext4: introduce new i_write_mutex to protect fallocate" from May 26, 2014, leads to the following static checker warning: fs/ext4/file.c:195 ext4_file_write_iter() warn: 'mutex:&EXT4_Iinode->i_write_mutex' is sometimes locked here and sometimes unlocked. fs/ext4/file.c 104 mutex_lock(&EXT4_I(inode)->i_write_mutex); 105 106 /* 107 * Unaligned direct AIO must be serialized; see comment above 108 * In the case of O_APPEND, assume that we must always serialize 109 */ 110 if (o_direct && 111 ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) && 112 !is_sync_kiocb(iocb) && 113 (file->f_flags & O_APPEND || 114 ext4_unaligned_aio(inode, from, pos))) { 115 unaligned_direct_aio = true; 116 ext4_unwritten_wait(inode); 117 } 118 119 mutex_lock(&inode->i_mutex); 120 if (file->f_flags & O_APPEND) 121 iocb->ki_pos = pos = i_size_read(inode); 122 123 /* 124 * If we have encountered a bitmap-format file, the size limit 125 * is smaller than s_maxbytes, which is for extent-mapped files. 126 */ 127 if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) { 128 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); 129 130 if ((pos > sbi->s_bitmap_maxbytes) || 131 (pos == sbi->s_bitmap_maxbytes && length > 0)) { 132 mutex_unlock(&inode->i_mutex); 133 ret = -EFBIG; We want to always unlock on this path but it only unlocks when "unaligned_direct_aio" is true. 134 goto errout; 135 } 136 [ snip ] 192 errout: 193 if (unaligned_direct_aio) 194 mutex_unlock(&EXT4_I(inode)->i_write_mutex); 195 return ret; 196 } regards, dan carpenter -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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