fs: Add uoff_t

In a recent commit, I inadvertently changed a comparison from being an
unsigned comparison (on 64-bit systems) to being a signed comparison
(which it had always been on 32-bit systems). This led to a sporadic
fstests failure.

To make sure this comparison is always unsigned, introduce a new type,
uoff_t which is the unsigned version of loff_t. Generally file sizes
are restricted to being a signed integer, but in these two places it is
convenient to pass -1 to indicate "up to the end of the file".

Signed-off-by: Matthew Wilcox (Oracle) <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Christian Brauner <[e-mail]>

include/linux/mm.h

···
 extern unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info);
 
 /* truncate.c */
-extern void truncate_inode_pages(struct address_space *, loff_t);
-extern void truncate_inode_pages_range(struct address_space *,
-				       loff_t lstart, loff_t lend);
-extern void truncate_inode_pages_final(struct address_space *);
+void truncate_inode_pages(struct address_space *mapping, loff_t lstart);
+void truncate_inode_pages_range(struct address_space *mapping, loff_t lstart,
+		uoff_t lend);
+void truncate_inode_pages_final(struct address_space *mapping);
 
 /* generic vm_area_ops exported for stackable file systems */
 extern vm_fault_t filemap_fault(struct vm_fault *vmf);

include/linux/shmem_fs.h

···
 					pgoff_t index, gfp_t gfp_mask);
 int shmem_writeout(struct folio *folio, struct swap_iocb **plug,
 		struct list_head *folio_list);
-void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end);
+void shmem_truncate_range(struct inode *inode, loff_t start, uoff_t end);
 int shmem_unuse(unsigned int type);
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE

include/linux/types.h

···
 
 #if defined(__GNUC__)
 typedef __kernel_loff_t		loff_t;
+typedef __kernel_uoff_t		uoff_t;
 #endif
 
 /*

include/uapi/asm-generic/posix_types.h

···
  */
 typedef __kernel_long_t	__kernel_off_t;
 typedef long long	__kernel_loff_t;
+typedef unsigned long long	__kernel_uoff_t;
 typedef __kernel_long_t	__kernel_old_time_t;
 #ifndef __KERNEL__
 typedef __kernel_long_t	__kernel_time_t;

mm/shmem.c

···
  * Remove range of pages and swap entries from page cache, and free them.
  * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
  */
-static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
+static void shmem_undo_range(struct inode *inode, loff_t lstart, uoff_t lend,
 								 bool unfalloc)
 {
 	struct address_space *mapping = inode->i_mapping;
···
 	shmem_recalc_inode(inode, 0, -nr_swaps_freed);
 }
 
-void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
+void shmem_truncate_range(struct inode *inode, loff_t lstart, uoff_t lend)
 {
 	shmem_undo_range(inode, lstart, lend, false);
 	inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
···
 }
 #endif
 
-void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
+void shmem_truncate_range(struct inode *inode, loff_t lstart, uoff_t lend)
 {
 	truncate_inode_pages_range(inode->i_mapping, lstart, lend);
 }

mm/truncate.c

···
  * page aligned properly.
  */
 void truncate_inode_pages_range(struct address_space *mapping,
-				loff_t lstart, loff_t lend)
+				loff_t lstart, uoff_t lend)
 {
 	pgoff_t		start;		/* inclusive */
 	pgoff_t		end;		/* exclusive */