linux-kernel - [RFC PATCH v4 07/11] fs: statx add write zeroes unmap attribute

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Message-ID: <20250421021509.2366003-8-yi.zhang@huaweicloud.com>
Date: Mon, 21 Apr 2025 10:15:05 +0800
From: Zhang Yi <yi.zhang@...weicloud.com>
To: linux-fsdevel@...r.kernel.org,
	linux-ext4@...r.kernel.org,
	linux-block@...r.kernel.org,
	dm-devel@...ts.linux.dev,
	linux-nvme@...ts.infradead.org,
	linux-scsi@...r.kernel.org
Cc: linux-xfs@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	hch@....de,
	tytso@....edu,
	djwong@...nel.org,
	john.g.garry@...cle.com,
	bmarzins@...hat.com,
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	shinichiro.kawasaki@....com,
	brauner@...nel.org,
	yi.zhang@...wei.com,
	yi.zhang@...weicloud.com,
	chengzhihao1@...wei.com,
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	yangerkun@...wei.com
Subject: [RFC PATCH v4 07/11] fs: statx add write zeroes unmap attribute

From: Zhang Yi <yi.zhang@...wei.com>

Add a new attribute flag to statx to determine whether a bdev or a file
supports the unmap write zeroes command.

Signed-off-by: Zhang Yi <yi.zhang@...wei.com>
---
 block/bdev.c              | 4 ++++
 fs/ext4/inode.c           | 9 ++++++---
 include/uapi/linux/stat.h | 1 +
 3 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/block/bdev.c b/block/bdev.c
index 4844d1e27b6f..29b0e5feb138 100644
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -1304,6 +1304,10 @@ void bdev_statx(struct path *path, struct kstat *stat,
 			queue_atomic_write_unit_max_bytes(bd_queue));
 	}
 
+	if (bdev_write_zeroes_unmap(bdev))
+		stat->attributes |= STATX_ATTR_WRITE_ZEROES_UNMAP;
+	stat->attributes_mask |= STATX_ATTR_WRITE_ZEROES_UNMAP;
+
 	stat->blksize = bdev_io_min(bdev);
 
 	blkdev_put_no_open(bdev);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 94c7d2d828a6..38caf2f39c6d 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5653,6 +5653,7 @@ int ext4_getattr(struct mnt_idmap *idmap, const struct path *path,
 	struct inode *inode = d_inode(path->dentry);
 	struct ext4_inode *raw_inode;
 	struct ext4_inode_info *ei = EXT4_I(inode);
+	struct block_device *bdev = inode->i_sb->s_bdev;
 	unsigned int flags;
 
 	if ((request_mask & STATX_BTIME) &&
@@ -5672,8 +5673,6 @@ int ext4_getattr(struct mnt_idmap *idmap, const struct path *path,
 
 		stat->result_mask |= STATX_DIOALIGN;
 		if (dio_align == 1) {
-			struct block_device *bdev = inode->i_sb->s_bdev;
-
 			/* iomap defaults */
 			stat->dio_mem_align = bdev_dma_alignment(bdev) + 1;
 			stat->dio_offset_align = bdev_logical_block_size(bdev);
@@ -5695,6 +5694,9 @@ int ext4_getattr(struct mnt_idmap *idmap, const struct path *path,
 		generic_fill_statx_atomic_writes(stat, awu_min, awu_max);
 	}
 
+	if (S_ISREG(inode->i_mode) && bdev_write_zeroes_unmap(bdev))
+		stat->attributes |= STATX_ATTR_WRITE_ZEROES_UNMAP;
+
 	flags = ei->i_flags & EXT4_FL_USER_VISIBLE;
 	if (flags & EXT4_APPEND_FL)
 		stat->attributes |= STATX_ATTR_APPEND;
@@ -5714,7 +5716,8 @@ int ext4_getattr(struct mnt_idmap *idmap, const struct path *path,
 				  STATX_ATTR_ENCRYPTED |
 				  STATX_ATTR_IMMUTABLE |
 				  STATX_ATTR_NODUMP |
-				  STATX_ATTR_VERITY);
+				  STATX_ATTR_VERITY |
+				  STATX_ATTR_WRITE_ZEROES_UNMAP);
 
 	generic_fillattr(idmap, request_mask, inode, stat);
 	return 0;
diff --git a/include/uapi/linux/stat.h b/include/uapi/linux/stat.h
index f78ee3670dd5..279ce7e34df7 100644
--- a/include/uapi/linux/stat.h
+++ b/include/uapi/linux/stat.h
@@ -251,6 +251,7 @@ struct statx {
 #define STATX_ATTR_VERITY		0x00100000 /* [I] Verity protected file */
 #define STATX_ATTR_DAX			0x00200000 /* File is currently in DAX state */
 #define STATX_ATTR_WRITE_ATOMIC		0x00400000 /* File supports atomic write operations */
+#define STATX_ATTR_WRITE_ZEROES_UNMAP	0x00800000 /* File supports unmap write zeroes */
 
 
 #endif /* _UAPI_LINUX_STAT_H */
-- 
2.46.1