Return type for fault handlers  in ext4 and nilfs are
changed to use vm_fault_t.

Return type of block_page_mkwrite() is changed from
int to vm_fault_t. The function signature of
block_page_mkwrite() is changed to add one new parameter
int *err. This will provide a way for caller functions
to get error value along with return value and use it
further.

Return type of block_page_mkwrite_return() is also changed
to use new vm_fault_t type.

Signed-off-by: Souptick Joarder <jrdr.li...@gmail.com>
---
v2: return type of nilfs_page_mkwrite() changed to vm_fault_t
    Address Ryusuke's comment. remove err =0.

 fs/buffer.c                 | 20 +++++++++++---------
 fs/ext4/ext4.h              |  4 ++--
 fs/ext4/inode.c             | 31 +++++++++++++++----------------
 fs/nilfs2/file.c            | 17 ++++++++++-------
 include/linux/buffer_head.h |  7 ++++---
 5 files changed, 42 insertions(+), 37 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index cabc045..94b8086 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2444,21 +2444,21 @@ int block_commit_write(struct page *page, unsigned 
from, unsigned to)
  * Direct callers of this function should protect against filesystem freezing
  * using sb_start_pagefault() - sb_end_pagefault() functions.
  */
-int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
-                        get_block_t get_block)
+vm_fault_t block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
+                        get_block_t get_block, int *err)
 {
        struct page *page = vmf->page;
        struct inode *inode = file_inode(vma->vm_file);
        unsigned long end;
        loff_t size;
-       int ret;
+       int err1;
 
        lock_page(page);
        size = i_size_read(inode);
        if ((page->mapping != inode->i_mapping) ||
            (page_offset(page) > size)) {
                /* We overload EFAULT to mean page got truncated */
-               ret = -EFAULT;
+               err1 = -EFAULT;
                goto out_unlock;
        }
 
@@ -2468,18 +2468,20 @@ int block_page_mkwrite(struct vm_area_struct *vma, 
struct vm_fault *vmf,
        else
                end = PAGE_SIZE;
 
-       ret = __block_write_begin(page, 0, end, get_block);
-       if (!ret)
-               ret = block_commit_write(page, 0, end);
+       err1 = __block_write_begin(page, 0, end, get_block);
+       if (!err1)
+               err1 = block_commit_write(page, 0, end);
 
-       if (unlikely(ret < 0))
+       if (unlikely(err1 < 0))
                goto out_unlock;
+       *err = err1;
        set_page_dirty(page);
        wait_for_stable_page(page);
        return 0;
 out_unlock:
        unlock_page(page);
-       return ret;
+       *err = err1;
+       return block_page_mkwrite_return(err1);
 }
 EXPORT_SYMBOL(block_page_mkwrite);
 
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 7c7123f..bff7b42 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2465,8 +2465,8 @@ int do_journal_get_write_access(handle_t *handle,
 extern int ext4_chunk_trans_blocks(struct inode *, int nrblocks);
 extern int ext4_zero_partial_blocks(handle_t *handle, struct inode *inode,
                             loff_t lstart, loff_t lend);
-extern int ext4_page_mkwrite(struct vm_fault *vmf);
-extern int ext4_filemap_fault(struct vm_fault *vmf);
+extern vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf);
+extern vm_fault_t ext4_filemap_fault(struct vm_fault *vmf);
 extern qsize_t *ext4_get_reserved_space(struct inode *inode);
 extern int ext4_get_projid(struct inode *inode, kprojid_t *projid);
 extern void ext4_da_update_reserve_space(struct inode *inode,
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 7d6c100..c597483 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -6109,27 +6109,27 @@ static int ext4_bh_unmapped(handle_t *handle, struct 
buffer_head *bh)
        return !buffer_mapped(bh);
 }
 
-int ext4_page_mkwrite(struct vm_fault *vmf)
+vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf)
 {
        struct vm_area_struct *vma = vmf->vma;
        struct page *page = vmf->page;
        loff_t size;
        unsigned long len;
-       int ret;
+       vm_fault_t ret;
        struct file *file = vma->vm_file;
        struct inode *inode = file_inode(file);
        struct address_space *mapping = inode->i_mapping;
        handle_t *handle;
        get_block_t *get_block;
-       int retries = 0;
+       int retries = 0, err;
 
        sb_start_pagefault(inode->i_sb);
        file_update_time(vma->vm_file);
 
        down_read(&EXT4_I(inode)->i_mmap_sem);
 
-       ret = ext4_convert_inline_data(inode);
-       if (ret)
+       err = ext4_convert_inline_data(inode);
+       if (err)
                goto out_ret;
 
        /* Delalloc case is easy... */
@@ -6138,10 +6138,10 @@ int ext4_page_mkwrite(struct vm_fault *vmf)
            !ext4_nonda_switch(inode->i_sb)) {
                do {
                        ret = block_page_mkwrite(vma, vmf,
-                                                  ext4_da_get_block_prep);
-               } while (ret == -ENOSPC &&
+                                               ext4_da_get_block_prep, &err);
+               } while (err == -ENOSPC &&
                       ext4_should_retry_alloc(inode->i_sb, &retries));
-               goto out_ret;
+               goto out;
        }
 
        lock_page(page);
@@ -6184,36 +6184,35 @@ int ext4_page_mkwrite(struct vm_fault *vmf)
                ret = VM_FAULT_SIGBUS;
                goto out;
        }
-       ret = block_page_mkwrite(vma, vmf, get_block);
+       ret = block_page_mkwrite(vma, vmf, get_block, &err);
        if (!ret && ext4_should_journal_data(inode)) {
                if (ext4_walk_page_buffers(handle, page_buffers(page), 0,
                          PAGE_SIZE, NULL, do_journal_get_write_access)) {
                        unlock_page(page);
-                       ret = VM_FAULT_SIGBUS;
                        ext4_journal_stop(handle);
                        goto out;
                }
                ext4_set_inode_state(inode, EXT4_STATE_JDATA);
        }
        ext4_journal_stop(handle);
-       if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
+       if (err == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
                goto retry_alloc;
 out_ret:
-       ret = block_page_mkwrite_return(ret);
+       ret = block_page_mkwrite_return(err);
 out:
        up_read(&EXT4_I(inode)->i_mmap_sem);
        sb_end_pagefault(inode->i_sb);
        return ret;
 }
 
-int ext4_filemap_fault(struct vm_fault *vmf)
+vm_fault_t ext4_filemap_fault(struct vm_fault *vmf)
 {
        struct inode *inode = file_inode(vmf->vma->vm_file);
-       int err;
+       vm_fault_t ret;
 
        down_read(&EXT4_I(inode)->i_mmap_sem);
-       err = filemap_fault(vmf);
+       ret = filemap_fault(vmf);
        up_read(&EXT4_I(inode)->i_mmap_sem);
 
-       return err;
+       return ret;
 }
diff --git a/fs/nilfs2/file.c b/fs/nilfs2/file.c
index c5fa3de..3533efe 100644
--- a/fs/nilfs2/file.c
+++ b/fs/nilfs2/file.c
@@ -51,13 +51,14 @@ int nilfs_sync_file(struct file *file, loff_t start, loff_t 
end, int datasync)
        return err;
 }
 
-static int nilfs_page_mkwrite(struct vm_fault *vmf)
+static vm_fault_t nilfs_page_mkwrite(struct vm_fault *vmf)
 {
        struct vm_area_struct *vma = vmf->vma;
        struct page *page = vmf->page;
        struct inode *inode = file_inode(vma->vm_file);
        struct nilfs_transaction_info ti;
-       int ret = 0;
+       vm_fault_t ret = VM_FAULT_LOCKED;
+       int err = 0;
 
        if (unlikely(nilfs_near_disk_full(inode->i_sb->s_fs_info)))
                return VM_FAULT_SIGBUS; /* -ENOSPC */
@@ -67,7 +68,7 @@ static int nilfs_page_mkwrite(struct vm_fault *vmf)
        if (page->mapping != inode->i_mapping ||
            page_offset(page) >= i_size_read(inode) || !PageUptodate(page)) {
                unlock_page(page);
-               ret = -EFAULT;  /* make the VM retry the fault */
+               ret = VM_FAULT_NOPAGE;  /* make the VM retry the fault */
                goto out;
        }
 
@@ -99,13 +100,15 @@ static int nilfs_page_mkwrite(struct vm_fault *vmf)
        /*
         * fill hole blocks
         */
-       ret = nilfs_transaction_begin(inode->i_sb, &ti, 1);
+       err = nilfs_transaction_begin(inode->i_sb, &ti, 1);
        /* never returns -ENOMEM, but may return -ENOSPC */
-       if (unlikely(ret))
+       if (unlikely(err)) {
+               ret = block_page_mkwrite_return(err);
                goto out;
+       }
 
        file_update_time(vma->vm_file);
-       ret = block_page_mkwrite(vma, vmf, nilfs_get_block);
+       ret = block_page_mkwrite(vma, vmf, nilfs_get_block, &err);
        if (ret) {
                nilfs_transaction_abort(inode->i_sb);
                goto out;
@@ -117,7 +120,7 @@ static int nilfs_page_mkwrite(struct vm_fault *vmf)
        wait_for_stable_page(page);
  out:
        sb_end_pagefault(inode->i_sb);
-       return block_page_mkwrite_return(ret);
+       return ret;
 }
 
 static const struct vm_operations_struct nilfs_file_vm_ops = {
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index 96225a7..e212b13 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -14,6 +14,7 @@
 #include <linux/pagemap.h>
 #include <linux/wait.h>
 #include <linux/atomic.h>
+#include <linux/mm_types.h>
 
 #ifdef CONFIG_BLOCK
 
@@ -239,10 +240,10 @@ int cont_write_begin(struct file *, struct address_space 
*, loff_t,
                        get_block_t *, loff_t *);
 int generic_cont_expand_simple(struct inode *inode, loff_t size);
 int block_commit_write(struct page *page, unsigned from, unsigned to);
-int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
-                               get_block_t get_block);
+vm_fault_t block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
+                               get_block_t get_block, int *err);
 /* Convert errno to return value from ->page_mkwrite() call */
-static inline int block_page_mkwrite_return(int err)
+static inline vm_fault_t block_page_mkwrite_return(int err)
 {
        if (err == 0)
                return VM_FAULT_LOCKED;
-- 
1.9.1

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