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Subject[PATCH 1/7] mm: add nofail version of vmtruncate() and inode_setattr()
Date
vmtrucate may fail due to IS_SWAPFILE flag or due to RLIMIT_FSIZE.
In some situations it is not acceptable behaviour. Off course
we can check IS_SWAPFILE before but what about RLIMIT_FSIZE?

Let's divide vmtruncate in two parts. One which perform necessery
checks and second(__vmtruncate) which can not fail. In this case
caller is responsible for necessery checks before calling
no_fail vmtruncate version.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
fs/attr.c | 22 ++++++++++++++++------
include/linux/fs.h | 1 +
include/linux/mm.h | 1 +
mm/truncate.c | 24 +++++++++++++++++-------
4 files changed, 35 insertions(+), 13 deletions(-)

diff --git a/fs/attr.c b/fs/attr.c
index 96d394b..b1cc391 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -105,16 +105,13 @@ out_big:
}
EXPORT_SYMBOL(inode_newsize_ok);

-int inode_setattr(struct inode * inode, struct iattr * attr)
+void __inode_setattr(struct inode * inode, struct iattr * attr)
{
unsigned int ia_valid = attr->ia_valid;

if (ia_valid & ATTR_SIZE &&
- attr->ia_size != i_size_read(inode)) {
- int error = vmtruncate(inode, attr->ia_size);
- if (error)
- return error;
- }
+ attr->ia_size != i_size_read(inode))
+ __vmtruncate(inode, attr->ia_size);

if (ia_valid & ATTR_UID)
inode->i_uid = attr->ia_uid;
@@ -138,6 +135,19 @@ int inode_setattr(struct inode * inode, struct iattr * attr)
}
mark_inode_dirty(inode);

+}
+EXPORT_SYMBOL(__inode_setattr);
+
+int inode_setattr(struct inode * inode, struct iattr * attr)
+{
+ int error;
+ if (attr->ia_valid & ATTR_SIZE &&
+ attr->ia_size != i_size_read(inode)) {
+ error = inode_newsize_ok(inode, attr->ia_size);
+ if (error)
+ return error;
+ }
+ __inode_setattr(inode, attr);
return 0;
}
EXPORT_SYMBOL(inode_setattr);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 9147ca8..18b7be8 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2373,6 +2373,7 @@ extern int buffer_migrate_page(struct address_space *,

extern int inode_change_ok(const struct inode *, struct iattr *);
extern int inode_newsize_ok(const struct inode *, loff_t offset);
+extern void __inode_setattr(struct inode *, struct iattr *);
extern int __must_check inode_setattr(struct inode *, struct iattr *);

extern void file_update_time(struct file *file);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 2265f28..d9fd667 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -808,6 +808,7 @@ static inline void unmap_shared_mapping_range(struct address_space *mapping,
}

extern void truncate_pagecache(struct inode *inode, loff_t old, loff_t new);
+extern void __vmtruncate(struct inode *inode, loff_t offset);
extern int vmtruncate(struct inode *inode, loff_t offset);
extern int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end);

diff --git a/mm/truncate.c b/mm/truncate.c
index 342deee..9253a5c 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -542,7 +542,8 @@ void truncate_pagecache(struct inode *inode, loff_t old, loff_t new)
EXPORT_SYMBOL(truncate_pagecache);

/**
- * vmtruncate - unmap mappings "freed" by truncate() syscall
+ * __vmtruncate - unmap mappings "freed" by truncate() syscall
+ * Caller must perform necessary checks before.
* @inode: inode of the file used
* @offset: file offset to start truncating
*
@@ -550,20 +551,29 @@ EXPORT_SYMBOL(truncate_pagecache);
* between the file and the memory map for a potential last
* incomplete page. Ugly, but necessary.
*/
-int vmtruncate(struct inode *inode, loff_t offset)
+void __vmtruncate(struct inode *inode, loff_t offset)
{
loff_t oldsize;
- int error;

- error = inode_newsize_ok(inode, offset);
- if (error)
- return error;
oldsize = inode->i_size;
i_size_write(inode, offset);
truncate_pagecache(inode, oldsize, offset);
if (inode->i_op->truncate)
inode->i_op->truncate(inode);
+}
+EXPORT_SYMBOL(__vmtruncate);

- return error;
+/**
+ * vmtruncate - unmap mappings "freed" by truncate() syscall
+ * @inode: inode of the file used
+ * @offset: file offset to start truncating
+ */
+int vmtruncate(struct inode *inode, loff_t offset)
+{
+ int error = inode_newsize_ok(inode, offset);
+ if (error)
+ return error;
+ __vmtruncate(inode, offset);
+ return 0;
}
EXPORT_SYMBOL(vmtruncate);
--
1.6.6


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