linux-ext4 - [PATCH v4 3/6] ext4: make the updating inode data procedure atomic

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Date:   Thu, 26 Aug 2021 21:04:09 +0800
From:   Zhang Yi <yi.zhang@...wei.com>
To:     <linux-ext4@...r.kernel.org>
CC:     <tytso@....edu>, <adilger.kernel@...ger.ca>, <jack@...e.cz>,
        <yi.zhang@...wei.com>, <yukuai3@...wei.com>
Subject: [PATCH v4 3/6] ext4: make the updating inode data procedure atomic

Now that ext4_do_update_inode() return error before filling the whole
inode data if we fail to set inode blocks in ext4_inode_blocks_set().
This error should never happen in theory since sb->s_maxbytes should not
have allowed this, we have already init sb->s_maxbytes according to this
feature in ext4_fill_super(). So even through that could only happen due
to the filesystem corruption, we'd better to return after we finish
updating the inode because it may left an uninitialized buffer and we
could read this buffer later in "errors=continue" mode.

This patch make the updating inode data procedure atomic, call
EXT4_ERROR_INODE() after we dropping i_raw_lock after something bad
happened, make sure that the inode is integrated, and also drop a BUG_ON
and do some small cleanups.

Signed-off-by: Zhang Yi <yi.zhang@...wei.com>
Reviewed-by: Jan Kara <jack@...e.cz>
---
 fs/ext4/inode.c | 44 ++++++++++++++++++++++++++++----------------
 1 file changed, 28 insertions(+), 16 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index eae1b2d0b550..8323d3e8f393 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4920,8 +4920,14 @@ static int ext4_inode_blocks_set(handle_t *handle,
 		ext4_clear_inode_flag(inode, EXT4_INODE_HUGE_FILE);
 		return 0;
 	}
+
+	/*
+	 * This should never happen since sb->s_maxbytes should not have
+	 * allowed this, sb->s_maxbytes was set according to the huge_file
+	 * feature in ext4_fill_super().
+	 */
 	if (!ext4_has_feature_huge_file(sb))
-		return -EFBIG;
+		return -EFSCORRUPTED;
 
 	if (i_blocks <= 0xffffffffffffULL) {
 		/*
@@ -5024,16 +5030,14 @@ static int ext4_do_update_inode(handle_t *handle,
 
 	spin_lock(&ei->i_raw_lock);
 
-	/* For fields not tracked in the in-memory inode,
-	 * initialise them to zero for new inodes. */
+	/*
+	 * For fields not tracked in the in-memory inode, initialise them
+	 * to zero for new inodes.
+	 */
 	if (ext4_test_inode_state(inode, EXT4_STATE_NEW))
 		memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
 
 	err = ext4_inode_blocks_set(handle, raw_inode, ei);
-	if (err) {
-		spin_unlock(&ei->i_raw_lock);
-		goto out_brelse;
-	}
 
 	raw_inode->i_mode = cpu_to_le16(inode->i_mode);
 	i_uid = i_uid_read(inode);
@@ -5042,10 +5046,11 @@ static int ext4_do_update_inode(handle_t *handle,
 	if (!(test_opt(inode->i_sb, NO_UID32))) {
 		raw_inode->i_uid_low = cpu_to_le16(low_16_bits(i_uid));
 		raw_inode->i_gid_low = cpu_to_le16(low_16_bits(i_gid));
-/*
- * Fix up interoperability with old kernels. Otherwise, old inodes get
- * re-used with the upper 16 bits of the uid/gid intact
- */
+		/*
+		 * Fix up interoperability with old kernels. Otherwise,
+		 * old inodes get re-used with the upper 16 bits of the
+		 * uid/gid intact.
+		 */
 		if (ei->i_dtime && list_empty(&ei->i_orphan)) {
 			raw_inode->i_uid_high = 0;
 			raw_inode->i_gid_high = 0;
@@ -5114,8 +5119,9 @@ static int ext4_do_update_inode(handle_t *handle,
 		}
 	}
 
-	BUG_ON(!ext4_has_feature_project(inode->i_sb) &&
-	       i_projid != EXT4_DEF_PROJID);
+	if (i_projid != EXT4_DEF_PROJID &&
+	    !ext4_has_feature_project(inode->i_sb))
+		err = err ?: -EFSCORRUPTED;
 
 	if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
 	    EXT4_FITS_IN_INODE(raw_inode, ei, i_projid))
@@ -5123,6 +5129,11 @@ static int ext4_do_update_inode(handle_t *handle,
 
 	ext4_inode_csum_set(inode, raw_inode, ei);
 	spin_unlock(&ei->i_raw_lock);
+	if (err) {
+		EXT4_ERROR_INODE(inode, "corrupted inode contents");
+		goto out_brelse;
+	}
+
 	if (inode->i_sb->s_flags & SB_LAZYTIME)
 		ext4_update_other_inodes_time(inode->i_sb, inode->i_ino,
 					      bh->b_data);
@@ -5130,13 +5141,13 @@ static int ext4_do_update_inode(handle_t *handle,
 	BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
 	err = ext4_handle_dirty_metadata(handle, NULL, bh);
 	if (err)
-		goto out_brelse;
+		goto out_error;
 	ext4_clear_inode_state(inode, EXT4_STATE_NEW);
 	if (set_large_file) {
 		BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get write access");
 		err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh);
 		if (err)
-			goto out_brelse;
+			goto out_error;
 		lock_buffer(EXT4_SB(sb)->s_sbh);
 		ext4_set_feature_large_file(sb);
 		ext4_superblock_csum_set(sb);
@@ -5146,9 +5157,10 @@ static int ext4_do_update_inode(handle_t *handle,
 						 EXT4_SB(sb)->s_sbh);
 	}
 	ext4_update_inode_fsync_trans(handle, inode, need_datasync);
+out_error:
+	ext4_std_error(inode->i_sb, err);
 out_brelse:
 	brelse(bh);
-	ext4_std_error(inode->i_sb, err);
 	return err;
 }
 
-- 
2.31.1