[PATCH] exfat: replace truncate_lock with inode_lock

[Chi Zhiling]

From: Chi Zhiling <chizhiling@xxxxxxxxxx>

Remove the per-inode truncate_lock and rely on inode_lock instead.
exfat_setattr() truncates under inode_lock (held exclusively by the
VFS callers), and exfat_aop_bmap() now takes inode_lock shared to
exclude a concurrent truncate, providing the same mutual exclusion
with a single lock.

Signed-off-by: Chi Zhiling <chizhiling@xxxxxxxxxx>
---
 fs/exfat/exfat_fs.h | 2 --
 fs/exfat/file.c     | 2 --
 fs/exfat/inode.c    | 5 ++---
 fs/exfat/super.c    | 1 -
 4 files changed, 2 insertions(+), 8 deletions(-)

diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
index fa30ab9d8564..a9131fe03302 100644
--- a/fs/exfat/exfat_fs.h
+++ b/fs/exfat/exfat_fs.h
@@ -298,8 +298,6 @@ struct exfat_inode_info {
 	loff_t zeroed_size;
 	/* hash by i_location */
 	struct hlist_node i_hash_fat;
-	/* protect bmap against truncate */
-	struct rw_semaphore truncate_lock;
 	struct inode vfs_inode;
 	/* File creation time */
 	struct timespec64 i_crtime;
diff --git a/fs/exfat/file.c b/fs/exfat/file.c
index 1c1524caaaf7..a2a9ee1a2004 100644
--- a/fs/exfat/file.c
+++ b/fs/exfat/file.c
@@ -413,7 +413,6 @@ int exfat_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		 * about to be freed.
 		 */
 		inode_dio_wait(inode);
-		down_write(&EXFAT_I(inode)->truncate_lock);
 		truncate_setsize(inode, attr->ia_size);
 
 		/*
@@ -421,7 +420,6 @@ int exfat_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		 * is already written by it, so mark_inode_dirty() is unneeded.
 		 */
 		exfat_truncate(inode);
-		up_write(&EXFAT_I(inode)->truncate_lock);
 	} else
 		mark_inode_dirty(inode);
 
diff --git a/fs/exfat/inode.c b/fs/exfat/inode.c
index 89826aea5e1e..ccd13630187e 100644
--- a/fs/exfat/inode.c
+++ b/fs/exfat/inode.c
@@ -291,10 +291,9 @@ static sector_t exfat_aop_bmap(struct address_space *mapping, sector_t block)
 {
 	sector_t blocknr;
 
-	/* exfat_get_cluster() assumes the requested blocknr isn't truncated. */
-	down_read(&EXFAT_I(mapping->host)->truncate_lock);
+	inode_lock_shared(mapping->host);
 	blocknr = iomap_bmap(mapping, block, &exfat_iomap_ops);
-	up_read(&EXFAT_I(mapping->host)->truncate_lock);
+	inode_unlock_shared(mapping->host);
 	return blocknr;
 }
 
diff --git a/fs/exfat/super.c b/fs/exfat/super.c
index 388db271c6bf..a9ea36ba2693 100644
--- a/fs/exfat/super.c
+++ b/fs/exfat/super.c
@@ -195,7 +195,6 @@ static struct inode *exfat_alloc_inode(struct super_block *sb)
 	if (!ei)
 		return NULL;
 
-	init_rwsem(&ei->truncate_lock);
 	return &ei->vfs_inode;
 }
 
-- 
2.53.0