ext2: Remove deprecated DAX support

DAX support in ext2 was deprecated in commit d5a2693 ("ext2:
Deprecate DAX") with a removal deadline of end of 2025.  Remove all DAX
code from ext2 as scheduled.

This removes the DAX mount option, IOMAP DAX support, DAX file
operations, DAX address_space_operations, and the DAX fault handler.

[JK: Fixup some whitespace damage]

Signed-off-by: Ashwin Gundarapu <linuxuser509@zohomail.in>
Link: https://patch.msgid.link/19e5aa07c9b.3a2e576d130187.5289857983023045470@zohomail.in
Signed-off-by: Jan Kara <jack@suse.cz>

Author: Ashwin Gundarapu

fs/ext2/ext2.h

@@ -114,8 +114,6 @@ struct ext2_sb_info {
 	 */
 	spinlock_t s_lock;
 	struct mb_cache *s_ea_block_cache;
-	struct dax_device *s_daxdev;
-	u64 s_dax_part_off;
 };
 
 static inline spinlock_t *
@@ -373,11 +371,9 @@ struct ext2_inode {
 #define EXT2_MOUNT_NO_UID32		0x000200  /* Disable 32-bit UIDs */
 #define EXT2_MOUNT_XATTR_USER		0x004000  /* Extended user attributes */
 #define EXT2_MOUNT_POSIX_ACL		0x008000  /* POSIX Access Control Lists */
-#define EXT2_MOUNT_XIP			0x010000  /* Obsolete, use DAX */
 #define EXT2_MOUNT_USRQUOTA		0x020000  /* user quota */
 #define EXT2_MOUNT_GRPQUOTA		0x040000  /* group quota */
 #define EXT2_MOUNT_RESERVATION		0x080000  /* Preallocation */
-#define EXT2_MOUNT_DAX			0x100000  /* Direct Access */
 
 
 #define clear_opt(o, opt)		o &= ~EXT2_MOUNT_##opt

fs/ext2/file.c

@@ -21,7 +21,6 @@
 
 #include <linux/time.h>
 #include <linux/pagemap.h>
-#include <linux/dax.h>
 #include <linux/filelock.h>
 #include <linux/quotaops.h>
 #include <linux/iomap.h>
@@ -32,111 +31,6 @@
 #include "acl.h"
 #include "trace.h"
 
-#ifdef CONFIG_FS_DAX
-static ssize_t ext2_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
-{
-	struct inode *inode = iocb->ki_filp->f_mapping->host;
-	ssize_t ret;
-
-	if (!iov_iter_count(to))
-		return 0; /* skip atime */
-
-	inode_lock_shared(inode);
-	ret = dax_iomap_rw(iocb, to, &ext2_iomap_ops);
-	inode_unlock_shared(inode);
-
-	file_accessed(iocb->ki_filp);
-	return ret;
-}
-
-static ssize_t ext2_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
-{
-	struct file *file = iocb->ki_filp;
-	struct inode *inode = file->f_mapping->host;
-	ssize_t ret;
-
-	inode_lock(inode);
-	ret = generic_write_checks(iocb, from);
-	if (ret <= 0)
-		goto out_unlock;
-	ret = file_remove_privs(file);
-	if (ret)
-		goto out_unlock;
-	ret = file_update_time(file);
-	if (ret)
-		goto out_unlock;
-
-	ret = dax_iomap_rw(iocb, from, &ext2_iomap_ops);
-	if (ret > 0 && iocb->ki_pos > i_size_read(inode)) {
-		i_size_write(inode, iocb->ki_pos);
-		mark_inode_dirty(inode);
-	}
-
-out_unlock:
-	inode_unlock(inode);
-	if (ret > 0)
-		ret = generic_write_sync(iocb, ret);
-	return ret;
-}
-
-/*
- * The lock ordering for ext2 DAX fault paths is:
- *
- * mmap_lock (MM)
- *   sb_start_pagefault (vfs, freeze)
- *     address_space->invalidate_lock
- *       address_space->i_mmap_rwsem or page_lock (mutually exclusive in DAX)
- *         ext2_inode_info->truncate_mutex
- *
- * The default page_lock and i_size verification done by non-DAX fault paths
- * is sufficient because ext2 doesn't support hole punching.
- */
-static vm_fault_t ext2_dax_fault(struct vm_fault *vmf)
-{
-	struct inode *inode = file_inode(vmf->vma->vm_file);
-	vm_fault_t ret;
-	bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
-		(vmf->vma->vm_flags & VM_SHARED);
-
-	if (write) {
-		sb_start_pagefault(inode->i_sb);
-		file_update_time(vmf->vma->vm_file);
-	}
-	filemap_invalidate_lock_shared(inode->i_mapping);
-
-	ret = dax_iomap_fault(vmf, 0, NULL, NULL, &ext2_iomap_ops);
-
-	filemap_invalidate_unlock_shared(inode->i_mapping);
-	if (write)
-		sb_end_pagefault(inode->i_sb);
-	return ret;
-}
-
-static const struct vm_operations_struct ext2_dax_vm_ops = {
-	.fault		= ext2_dax_fault,
-	/*
-	 * .huge_fault is not supported for DAX because allocation in ext2
-	 * cannot be reliably aligned to huge page sizes and so pmd faults
-	 * will always fail and fail back to regular faults.
-	 */
-	.page_mkwrite	= ext2_dax_fault,
-	.pfn_mkwrite	= ext2_dax_fault,
-};
-
-static int ext2_file_mmap_prepare(struct vm_area_desc *desc)
-{
-	struct file *file = desc->file;
-
-	if (!IS_DAX(file_inode(file)))
-		return generic_file_mmap_prepare(desc);
-
-	file_accessed(file);
-	desc->vm_ops = &ext2_dax_vm_ops;
-	return 0;
-}
-#else
-#define ext2_file_mmap_prepare	generic_file_mmap_prepare
-#endif
 
 /*
  * Called when filp is released. This happens when all file descriptors
@@ -285,10 +179,6 @@ static ssize_t ext2_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
 
 static ssize_t ext2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
-#ifdef CONFIG_FS_DAX
-	if (IS_DAX(iocb->ki_filp->f_mapping->host))
-		return ext2_dax_read_iter(iocb, to);
-#endif
 	if (iocb->ki_flags & IOCB_DIRECT)
 		return ext2_dio_read_iter(iocb, to);
 
@@ -297,10 +187,6 @@ static ssize_t ext2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 
 static ssize_t ext2_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
-#ifdef CONFIG_FS_DAX
-	if (IS_DAX(iocb->ki_filp->f_mapping->host))
-		return ext2_dax_write_iter(iocb, from);
-#endif
 	if (iocb->ki_flags & IOCB_DIRECT)
 		return ext2_dio_write_iter(iocb, from);
 
@@ -321,7 +207,7 @@ const struct file_operations ext2_file_operations = {
 #ifdef CONFIG_COMPAT
 	.compat_ioctl	= ext2_compat_ioctl,
 #endif
-	.mmap_prepare	= ext2_file_mmap_prepare,
+	.mmap_prepare	= generic_file_mmap_prepare,
 	.open		= ext2_file_open,
 	.release	= ext2_release_file,
 	.fsync		= ext2_fsync,

fs/ext2/inode.c

@@ -26,7 +26,6 @@
 #include <linux/time.h>
 #include <linux/highuid.h>
 #include <linux/pagemap.h>
-#include <linux/dax.h>
 #include <linux/blkdev.h>
 #include <linux/quotaops.h>
 #include <linux/writeback.h>
@@ -741,27 +740,6 @@ static int ext2_get_blocks(struct inode *inode,
 		goto cleanup;
 	}
 
-	if (IS_DAX(inode)) {
-		/*
-		 * We must unmap blocks before zeroing so that writeback cannot
-		 * overwrite zeros with stale data from block device page cache.
-		 */
-		clean_bdev_aliases(inode->i_sb->s_bdev,
-				   le32_to_cpu(chain[depth-1].key),
-				   count);
-		/*
-		 * block must be initialised before we put it in the tree
-		 * so that it's not found by another thread before it's
-		 * initialised
-		 */
-		err = sb_issue_zeroout(inode->i_sb,
-				le32_to_cpu(chain[depth-1].key), count,
-				GFP_KERNEL);
-		if (err) {
-			mutex_unlock(&ei->truncate_mutex);
-			goto cleanup;
-		}
-	}
 	*new = true;
 
 	ext2_splice_branch(inode, iblock, partial, indirect_blks, count);
@@ -811,7 +789,6 @@ static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 	unsigned int blkbits = inode->i_blkbits;
 	unsigned long first_block = offset >> blkbits;
 	unsigned long max_blocks = (length + (1 << blkbits) - 1) >> blkbits;
-	struct ext2_sb_info *sbi = EXT2_SB(inode->i_sb);
 	bool new = false, boundary = false;
 	u32 bno;
 	int ret;
@@ -841,10 +818,7 @@ static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 
 	iomap->flags = 0;
 	iomap->offset = (u64)first_block << blkbits;
-	if (flags & IOMAP_DAX)
-		iomap->dax_dev = sbi->s_daxdev;
-	else
-		iomap->bdev = inode->i_sb->s_bdev;
+	iomap->bdev = inode->i_sb->s_bdev;
 
 	if (ret == 0) {
 		/*
@@ -859,8 +833,6 @@ static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 	} else {
 		iomap->type = IOMAP_MAPPED;
 		iomap->addr = (u64)bno << blkbits;
-		if (flags & IOMAP_DAX)
-			iomap->addr += sbi->s_dax_part_off;
 		iomap->length = (u64)ret << blkbits;
 		iomap->flags |= IOMAP_F_MERGED;
 	}
@@ -962,13 +934,6 @@ ext2_writepages(struct address_space *mapping, struct writeback_control *wbc)
 	return mpage_writepages(mapping, wbc, ext2_get_block);
 }
 
-static int
-ext2_dax_writepages(struct address_space *mapping, struct writeback_control *wbc)
-{
-	struct ext2_sb_info *sbi = EXT2_SB(mapping->host->i_sb);
-
-	return dax_writeback_mapping_range(mapping, sbi->s_daxdev, wbc);
-}
 
 const struct address_space_operations ext2_aops = {
 	.dirty_folio		= block_dirty_folio,
@@ -984,10 +949,6 @@ const struct address_space_operations ext2_aops = {
 	.error_remove_folio	= generic_error_remove_folio,
 };
 
-static const struct address_space_operations ext2_dax_aops = {
-	.writepages		= ext2_dax_writepages,
-	.dirty_folio		= noop_dirty_folio,
-};
 
 /*
  * Probably it should be a library function... search for first non-zero word
@@ -1186,9 +1147,6 @@ 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(&inode->i_mapping->invalidate_lock));
-#endif
 
 	n = ext2_block_to_path(inode, iblock, offsets, NULL);
 	if (n == 0)
@@ -1290,12 +1248,7 @@ static int ext2_setsize(struct inode *inode, loff_t newsize)
 
 	inode_dio_wait(inode);
 
-	if (IS_DAX(inode))
-		error = dax_truncate_page(inode, newsize, NULL,
-					  &ext2_iomap_ops);
-	else
-		error = block_truncate_page(inode->i_mapping,
-				newsize, ext2_get_block);
+	error = block_truncate_page(inode->i_mapping, newsize, ext2_get_block);
 	if (error)
 		return error;
 
@@ -1363,7 +1316,7 @@ void ext2_set_inode_flags(struct inode *inode)
 	unsigned int flags = EXT2_I(inode)->i_flags;
 
 	inode->i_flags &= ~(S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME |
-				S_DIRSYNC | S_DAX);
+				S_DIRSYNC);
 	if (flags & EXT2_SYNC_FL)
 		inode->i_flags |= S_SYNC;
 	if (flags & EXT2_APPEND_FL)
@@ -1374,18 +1327,13 @@ void ext2_set_inode_flags(struct inode *inode)
 		inode->i_flags |= S_NOATIME;
 	if (flags & EXT2_DIRSYNC_FL)
 		inode->i_flags |= S_DIRSYNC;
-	if (test_opt(inode->i_sb, DAX) && S_ISREG(inode->i_mode))
-		inode->i_flags |= S_DAX;
 }
 
 void ext2_set_file_ops(struct inode *inode)
 {
 	inode->i_op = &ext2_file_inode_operations;
 	inode->i_fop = &ext2_file_operations;
-	if (IS_DAX(inode))
-		inode->i_mapping->a_ops = &ext2_dax_aops;
-	else
-		inode->i_mapping->a_ops = &ext2_aops;
+	inode->i_mapping->a_ops = &ext2_aops;
 }
 
 struct inode *ext2_iget (struct super_block *sb, unsigned long ino)