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Subject[PATCH v9 24/61] page cache: Rearrange address_space
Date
From: Matthew Wilcox <mawilcox@microsoft.com>

Change i_pages from a radix_tree_root to an xarray, convert the
documentation into kernel-doc format and change the order of the elements
to pack them better on 64-bit systems.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
---
include/linux/fs.h | 46 +++++++++++++++++++++++++++++++---------------
1 file changed, 31 insertions(+), 15 deletions(-)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index c75902f30bfb..bb0731c05246 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -389,24 +389,40 @@ int pagecache_write_end(struct file *, struct address_space *mapping,
loff_t pos, unsigned len, unsigned copied,
struct page *page, void *fsdata);

+/**
+ * struct address_space - Contents of a cacheable, mappable object.
+ * @host: Owner, either the inode or the block_device.
+ * @i_pages: Cached pages.
+ * @gfp_mask: Memory allocation flags to use for allocating pages.
+ * @i_mmap_writable: Number of VM_SHARED mappings.
+ * @i_mmap: Tree of private and shared mappings.
+ * @i_mmap_rwsem: Protects @i_mmap and @i_mmap_writable.
+ * @nrpages: Number of page entries, protected by the i_pages lock.
+ * @nrexceptional: Shadow or DAX entries, protected by the i_pages lock.
+ * @writeback_index: Writeback starts here.
+ * @a_ops: Methods.
+ * @flags: Error bits and flags (AS_*).
+ * @wb_err: The most recent error which has occurred.
+ * @private_lock: For use by the owner of the address_space.
+ * @private_list: For use by the owner of the address_space.
+ * @private_data: For use by the owner of the address_space.
+ */
struct address_space {
- struct inode *host; /* owner: inode, block_device */
- struct radix_tree_root i_pages; /* cached pages */
- atomic_t i_mmap_writable;/* count VM_SHARED mappings */
- struct rb_root_cached i_mmap; /* tree of private and shared mappings */
- struct rw_semaphore i_mmap_rwsem; /* protect tree, count, list */
- /* Protected by the i_pages lock */
- unsigned long nrpages; /* number of total pages */
- /* number of shadow or DAX exceptional entries */
+ struct inode *host;
+ struct xarray i_pages;
+ gfp_t gfp_mask;
+ atomic_t i_mmap_writable;
+ struct rb_root_cached i_mmap;
+ struct rw_semaphore i_mmap_rwsem;
+ unsigned long nrpages;
unsigned long nrexceptional;
- pgoff_t writeback_index;/* writeback starts here */
- const struct address_space_operations *a_ops; /* methods */
- unsigned long flags; /* error bits */
- spinlock_t private_lock; /* for use by the address_space */
- gfp_t gfp_mask; /* implicit gfp mask for allocations */
- struct list_head private_list; /* for use by the address_space */
- void *private_data; /* ditto */
+ pgoff_t writeback_index;
+ const struct address_space_operations *a_ops;
+ unsigned long flags;
errseq_t wb_err;
+ spinlock_t private_lock;
+ struct list_head private_list;
+ void *private_data;
} __attribute__((aligned(sizeof(long)))) __randomize_layout;
/*
* On most architectures that alignment is already the case; but
--
2.16.1
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