[RFC 05/10] fs/dax: Refactor wait for dax idle page

Alistair Popple
2024-04-11T00:58:07Z

A FS DAX page is considered idle when its refcount drops to one. This
is currently open-coded in all file systems supporting FS DAX. Move
the idle detection to a common function to make future changes easier.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
---
fs/ext4/inode.c | 5 +----
fs/fuse/dax.c | 4 +---
fs/xfs/xfs_file.c | 4 +---
include/linux/dax.h | 11 +++++++++++
4 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 4ce35f1..e9cef7d 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3868,10 +3868,7 @@ int ext4_break_layouts(struct inode *inode)
if (!page)
return 0;

- error = ___wait_var_event(&page->_refcount,
- atomic_read(&page->_refcount) == 1,
- TASK_INTERRUPTIBLE, 0, 0,
- ext4_wait_dax_page(inode));
+ error = dax_wait_page_idle(page, ext4_wait_dax_page, inode);
} while (error == 0);

return error;
diff --git a/fs/fuse/dax.c b/fs/fuse/dax.c
index 23904a6..8a62483 100644
--- a/fs/fuse/dax.c
+++ b/fs/fuse/dax.c
@@ -676,9 +676,7 @@ static int __fuse_dax_break_layouts(struct inode *inode, bool *retry,
return 0;

*retry = true;
- return ___wait_var_event(&page->_refcount,
- atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE,
- 0, 0, fuse_wait_dax_page(inode));
+ return dax_wait_page_idle(page, fuse_wait_dax_page, inode);
}

/* dmap_end == 0 leads to unmapping of whole file */
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 2037002..099cd70 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -849,9 +849,7 @@ xfs_break_dax_layouts(
return 0;

*retry = true;
- return ___wait_var_event(&page->_refcount,
- atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE,
- 0, 0, xfs_wait_dax_page(inode));
+ return dax_wait_page_idle(page, xfs_wait_dax_page, inode);
}

int
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 22cd990..bced4d4 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -212,6 +212,17 @@ int dax_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero,
int dax_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
const struct iomap_ops *ops);

+static inline int dax_wait_page_idle(struct page *page,
+ void (cb)(struct inode *),
+ struct inode *inode)
+{
+ int ret;
+
+ ret = ___wait_var_event(page, page_ref_count(page) == 1,
+ TASK_INTERRUPTIBLE, 0, 0, cb(inode));
+ return ret;
+}
+
#if IS_ENABLED(CONFIG_DAX)
int dax_read_lock(void);
void dax_read_unlock(int id);
--
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