[PATCH 3.16 011/245] ext4: only call ext4_truncate when size <= isize

Ben Hutchings
2020-04-23T23:17:53Z

From: Josef Bacik <jbacik@fb.com>

commit 3da40c7b089810ac9cf2bb1e59633f619f3a7312 upstream.

At LSF we decided that if we truncate up from isize we shouldn't trim
fallocated blocks that were fallocated with KEEP_SIZE and are past the
new i_size. This patch fixes ext4 to do this.

[ Completely reworked patch so that i_disksize would actually get set
when truncating up. Also reworked the code for handling truncate so
that it's easier to handle. -- tytso ]

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>
[bwh: Backported to 3.16 as dependency of commit ea3d7209ca01
"ext4: fix races between page faults and hole punching":
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
fs/ext4/inode.c | 38 ++++++++++++++++++--------------------
1 file changed, 18 insertions(+), 20 deletions(-)

--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4809,8 +4809,10 @@ int ext4_setattr(struct dentry *dentry,
ext4_journal_stop(handle);
}

- if (attr->ia_valid & ATTR_SIZE && attr->ia_size != inode->i_size) {
+ if (attr->ia_valid & ATTR_SIZE) {
handle_t *handle;
+ loff_t oldsize = inode->i_size;
+ int shrink = (attr->ia_size <= inode->i_size);

if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
@@ -4818,24 +4820,26 @@ int ext4_setattr(struct dentry *dentry,
if (attr->ia_size > sbi->s_bitmap_maxbytes)
return -EFBIG;
}
+ if (!S_ISREG(inode->i_mode))
+ return -EINVAL;

if (IS_I_VERSION(inode) && attr->ia_size != inode->i_size)
inode_inc_iversion(inode);

- if (S_ISREG(inode->i_mode) &&
+ if (ext4_should_order_data(inode) &&
(attr->ia_size < inode->i_size)) {
- if (ext4_should_order_data(inode)) {
- error = ext4_begin_ordered_truncate(inode,
+ error = ext4_begin_ordered_truncate(inode,
attr->ia_size);
- if (error)
- goto err_out;
- }
+ if (error)
+ goto err_out;
+ }
+ if (attr->ia_size != inode->i_size) {
handle = ext4_journal_start(inode, EXT4_HT_INODE, 3);
if (IS_ERR(handle)) {
error = PTR_ERR(handle);
goto err_out;
}
- if (ext4_handle_valid(handle)) {
+ if (ext4_handle_valid(handle) && shrink) {
error = ext4_orphan_add(handle, inode);
orphan = 1;
}
@@ -4854,15 +4858,13 @@ int ext4_setattr(struct dentry *dentry,
up_write(&EXT4_I(inode)->i_data_sem);
ext4_journal_stop(handle);
if (error) {
- ext4_orphan_del(NULL, inode);
+ if (orphan)
+ ext4_orphan_del(NULL, inode);
goto err_out;
}
- } else {
- loff_t oldsize = inode->i_size;
-
- i_size_write(inode, attr->ia_size);
- pagecache_isize_extended(inode, oldsize, inode->i_size);
}
+ if (!shrink)
+ pagecache_isize_extended(inode, oldsize, inode->i_size);

/*
* Blocks are going to be removed from the inode. Wait
@@ -4882,13 +4884,9 @@ int ext4_setattr(struct dentry *dentry,
* in data=journal mode to make pages freeable.
*/
truncate_pagecache(inode, inode->i_size);
+ if (shrink)
+ ext4_truncate(inode);
}
- /*
- * We want to call ext4_truncate() even if attr->ia_size ==
- * inode->i_size for cases like truncation of fallocated space
- */
- if (attr->ia_valid & ATTR_SIZE)
- ext4_truncate(inode);

if (!rc) {
setattr_copy(inode, attr);