[PATCH v4 03/12] ext2, dax: finish implementing dax_sem helpers

[Dan Williams]

dax_sem_{up,down}_write_sem() allow the ext2 dax semaphore to be compiled
out in the CONFIG_FS_DAX=n case. However there are still some open coded
uses of the semaphore. Add dax_sem_{up_read,down_read,_is_locked}()
helpers and convert all open-coded usages of the semaphore to the
helpers.

Cc: Jan Kara <j...@suse.com>
Cc: <sta...@vger.kernel.org>
Fixes: dee410792419 ("/dev/dax, core: file operations and dax-mmap")
Signed-off-by: Dan Williams <dan.j.willi...@intel.com>
---
 fs/ext2/ext2.h  |    6 ++++++
 fs/ext2/file.c  |    5 ++---
 fs/ext2/inode.c |    4 +---
 3 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
index 032295e1d386..7ceb29733cdb 100644
--- a/fs/ext2/ext2.h
+++ b/fs/ext2/ext2.h
@@ -711,9 +711,15 @@ struct ext2_inode_info {
 #ifdef CONFIG_FS_DAX
 #define dax_sem_down_write(ext2_inode) down_write(&(ext2_inode)->dax_sem)
 #define dax_sem_up_write(ext2_inode)   up_write(&(ext2_inode)->dax_sem)
+#define dax_sem_is_locked(ext2_inode)  rwsem_is_locked(&(ext2_inode)->dax_sem)
+#define dax_sem_down_read(ext2_inode)  down_read(&(ext2_inode)->dax_sem)
+#define dax_sem_up_read(ext2_inode)    up_read(&(ext2_inode)->dax_sem)
 #else
 #define dax_sem_down_write(ext2_inode)
 #define dax_sem_up_write(ext2_inode)
+#define dax_sem_is_locked(ext2_inode)  (true)
+#define dax_sem_down_read(ext2_inode)
+#define dax_sem_up_read(ext2_inode)
 #endif
 
 /*
diff --git a/fs/ext2/file.c b/fs/ext2/file.c
index 09640220fda8..1c7ea1bcddde 100644
--- a/fs/ext2/file.c
+++ b/fs/ext2/file.c
@@ -91,18 +91,17 @@ static ssize_t ext2_dax_write_iter(struct kiocb *iocb, 
struct iov_iter *from)
 static int ext2_dax_fault(struct vm_fault *vmf)
 {
        struct inode *inode = file_inode(vmf->vma->vm_file);
-       struct ext2_inode_info *ei = EXT2_I(inode);
        int ret;
 
        if (vmf->flags & FAULT_FLAG_WRITE) {
                sb_start_pagefault(inode->i_sb);
                file_update_time(vmf->vma->vm_file);
        }
-       down_read(&ei->dax_sem);
+       dax_sem_down_read(EXT2_I(inode));
 
        ret = dax_iomap_fault(vmf, PE_SIZE_PTE, NULL, NULL, &ext2_iomap_ops);
 
-       up_read(&ei->dax_sem);
+       dax_sem_up_read(EXT2_I(inode));
        if (vmf->flags & FAULT_FLAG_WRITE)
                sb_end_pagefault(inode->i_sb);
        return ret;
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 9b2ac55ac34f..e04295e99d90 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -1187,9 +1187,7 @@ static void __ext2_truncate_blocks(struct inode *inode, 
loff_t offset)
        blocksize = inode->i_sb->s_blocksize;
        iblock = (offset + blocksize-1) >> EXT2_BLOCK_SIZE_BITS(inode->i_sb);
 
-#ifdef CONFIG_FS_DAX
-       WARN_ON(!rwsem_is_locked(&ei->dax_sem));
-#endif
+       WARN_ON(!dax_sem_is_locked(ei));
 
        n = ext2_block_to_path(inode, iblock, offsets, NULL);
        if (n == 0)