ocfs2: fix issue that ocfs2_setattr() does not deal with new_i_size==i_size

The issue scenario is as following:
1. fallocate a large disk space(eg. 30G) with FALLOC_FL_KEEP_SIZE for a file whose i_size and disk size are 512(or other size). After executing fallocate, i_size file is still 512, and the disk size became to 30G+512?
2. ftruncate the file to new_i_size which equal to inode->i_size. After executing ftruncate, disk space does not changes. In other words, i_size file is still 512, and disk size is 30G+512. But we want disk size to be 512.
This does not meet our expectations.

In order to Solving the issue above, we modified ocfs2_setattr(), if attr->ia_size != i_size_read(inode), It calls ocfs2_truncate_file(), and truncate disk space to attr->ia_size.

Signed-off-by Younger Liu <[email protected]>

---
 fs/ocfs2/alloc.c |    2 +-
 fs/ocfs2/file.c  |    7 ++-----
 2 files changed, 3 insertions(+), 6 deletions(-)

fs/ocfs2/alloc.c +1 -1

index b8a9d87..19837d4 100644
@@ -7126,7 +7126,7 @@ int ocfs2_truncate_inline(struct inode *inode, struct buffer_head *di_bh,
 	if (end > i_size_read(inode))
 		end = i_size_read(inode);
 
-	BUG_ON(start >= end);
+	BUG_ON(start > end);
 
 	if (!(OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) ||
 	    !(le16_to_cpu(di->i_dyn_features) & OCFS2_INLINE_DATA_FL) ||

fs/ocfs2/file.c +2 -5

index 793c010..2e405e8 100644
@@ -476,9 +476,6 @@ static int ocfs2_truncate_file(struct inode *inode,
 
 	/* lets handle the simple truncate cases before doing any more
 	 * cluster locking. */
-	if (new_i_size == le64_to_cpu(fe->i_size))
-		goto bail;
-
 	down_write(&OCFS2_I(inode)->ip_alloc_sem);
 
 	ocfs2_resv_discard(&osb->osb_la_resmap,

@@ -1150,14 +1147,14 @@ int ocfs2_setattr(struct dentry *dentry, struct iattr *attr)
 		goto bail_unlock_rw;
 	}
 
-	if (size_change && attr->ia_size != i_size_read(inode)) {
+	if (size_change) {
 		status = inode_newsize_ok(inode, attr->ia_size);
 		if (status)
 			goto bail_unlock;
 
 		inode_dio_wait(inode);
 
-		if (i_size_read(inode) > attr->ia_size) {
+		if (i_size_read(inode) >= attr->ia_size) {
 			if (ocfs2_should_order_data(inode)) {
 				status = ocfs2_begin_ordered_truncate(inode,
 								      attr->ia_size);

The issue scenario is as following:
1. fallocate a large disk space(eg. 30G) with FALLOC_FL_KEEP_SIZE for a file whose i_size and disk size are 512(or other size). After executing fallocate, i_size file is still 512, and the disk size became to 30G+512?

2. ftruncate the file to new_i_size which equal to inode->i_size. After executing ftruncate, disk space does not changes.

In other words, i_size file is still 512, and disk size is 30G+512. But we want disk size to be 512.

This does not meet our expectations.

In order to Solving the issue above, we modified ocfs2_setattr(), if attr->ia_size != i_size_read(inode), It calls ocfs2_truncate_file(), and truncate disk space to attr->ia_size.

Signed-off-by Younger Liu <[email protected]>

---
 fs/ocfs2/alloc.c |    2 +-
 fs/ocfs2/file.c  |    7 ++-----
 2 files changed, 3 insertions(+), 6 deletions(-)

fs/ocfs2/alloc.c +1 -1

index b8a9d87..19837d4 100644
@@ -7126,7 +7126,7 @@ int ocfs2_truncate_inline(struct inode *inode, struct buffer_head *di_bh,
 	if (end > i_size_read(inode))
 		end = i_size_read(inode);
 
-	BUG_ON(start >= end);
+	BUG_ON(start > end);
 
 	if (!(OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) ||
 	    !(le16_to_cpu(di->i_dyn_features) & OCFS2_INLINE_DATA_FL) ||

fs/ocfs2/file.c +0 -0

index 793c010..2e405e8 100644

fs/ocfs2/file.c +1 -4

-	if (new_i_size == le64_to_cpu(fe->i_size))
-		goto bail;
-
 	down_write(&OCFS2_I(inode)->ip_alloc_sem);
 
 	ocfs2_resv_discard(&osb->osb_la_resmap,

@@ -1150,14 +1147,14 @@ int ocfs2_setattr(struct dentry *dentry, struct iattr *attr)
 		goto bail_unlock_rw;
 	}
 
-	if (size_change && attr->ia_size != i_size_read(inode)) {
+	if (size_change) {
 		status = inode_newsize_ok(inode, attr->ia_size);

Thanks for your patch, it indeed fixed a bug. However, your description is not correct, please see my inline comments.

Quoted 5 lines · Younger Liu

The issue scenario is as following:
1. fallocate a large disk space(eg. 30G) with FALLOC_FL_KEEP_SIZE for a file whose i_size and disk size are 512(or other size). After executing fallocate, i_size file is still 512, and the disk size became to 30G+512?

The file size won't be changed if FALLOC_FL_KEEP_SIZE is specified, Pls refer to the man page of fallocate(2) for detail.

Disk size should be changed to reflect this operation, why not?

Quoted 2 lines

2. ftruncate the file to new_i_size which equal to inode->i_size. After executing ftruncate, disk space does not changes.

This is a real bug that be fixed in this patch.

Quoted 2 lines

In other words, i_size file is still 512, and disk size is 30G+512. But we want disk size to be 512.

Ditto.

Quoted 1 line

This does not meet our expectations.

...

Quoted 4 lines

In order to Solving the issue above, we modified ocfs2_setattr(), if attr->ia_size != i_size_read(inode), It calls ocfs2_truncate_file(), and truncate disk space to attr->ia_size.

Right.

Quoted 25 lines

Signed-off-by Younger Liu <[email protected]>

---
 fs/ocfs2/alloc.c |    2 +-
 fs/ocfs2/file.c  |    7 ++-----
 2 files changed, 3 insertions(+), 6 deletions(-)

fs/ocfs2/alloc.c +1 -1

index b8a9d87..19837d4 100644
@@ -7126,7 +7126,7 @@ int ocfs2_truncate_inline(struct inode *inode, struct buffer_head *di_bh,
 	if (end > i_size_read(inode))
 		end = i_size_read(inode);
 
-	BUG_ON(start >= end);
+	BUG_ON(start > end);
 
 	if (!(OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) ||
 	    !(le16_to_cpu(di->i_dyn_features) & OCFS2_INLINE_DATA_FL) ||

fs/ocfs2/file.c +0 -0

index 793c010..2e405e8 100644

fs/ocfs2/file.c static int ocfs2_truncate_file(struct inode *inode, · line 478

Quoted 3 lines

fs/ocfs2/file.c +0 -0

@@ -476,9 +476,6 @@ static int ocfs2_truncate_file(struct inode *inode,
 
 	/* lets handle the simple truncate cases before doing any more
 	 * cluster locking. */

Above pointless comments should be removed with this change as well.

Quoted 13 lines

fs/ocfs2/file.c +1 -4

-	if (new_i_size == le64_to_cpu(fe->i_size))
-		goto bail;
-
 	down_write(&OCFS2_I(inode)->ip_alloc_sem);
 
 	ocfs2_resv_discard(&osb->osb_la_resmap,

@@ -1150,14 +1147,14 @@ int ocfs2_setattr(struct dentry *dentry, struct iattr *attr)
 		goto bail_unlock_rw;
 	}
 
-	if (size_change && attr->ia_size != i_size_read(inode)) {
+	if (size_change) {
 		status = inode_newsize_ok(inode, attr->ia_size);

fs/ocfs2/file.c int ocfs2_setattr(struct dentry *dentry, struct iattr *attr) · line 1160

Quoted 10 lines

fs/ocfs2/file.c +1 -1

 		if (status)
 			goto bail_unlock;
 
 		inode_dio_wait(inode);
 
-		if (i_size_read(inode) > attr->ia_size) {
+		if (i_size_read(inode) >= attr->ia_size) {
 			if (ocfs2_should_order_data(inode)) {
 				status = ocfs2_begin_ordered_truncate(inode,
 								      attr->ia_size);

So I also run a quick test to verify this patch, it looks fine.

# dd if=/dev/zero of=/ocfs2/test bs=512 count=1
1+0 records in
1+0 records out
512 bytes (512 B) copied, 0.000150857 s, 3.4 MB/s

# xfs_io -c 'falloc -k 512 3G' /ocfs2/test
# ls -l /ocfs2/test
-rw-r--r-- 1 root root 512 Jun 28 11:47 /ocfs2/test
# df -h
Filesystem      Size  Used Avail Use% Mounted on
....
/dev/sdb1       8.0G  3.4G  4.7G  42% /ocfs2

# xfs_io -c 'truncate 512' /ocfs2/test

# df -h
Filesystem      Size  Used Avail Use% Mounted on
.....
/dev/sdb1       8.0G  363M  7.7G   5% /ocfs2

# ls -l /ocfs2/test
-rw-r--r-- 1 root root 512 Jun 28 11:47 /ocfs2/test

With above bug description problems were fixed, you can consider to add:

Reviewed-by Jie Liu <[email protected]>

Tested-by Jie Liu <[email protected]>

-Jeff

.