[PATCH 02/12] fs/ceph/super: make field `i_truncate_pagecache_size` optional

[Max Kellermann]

This field is only used with CONFIG_FS_ENCRYPTION; without it, it
always equals `i_truncate_size`.

This reduces the size of `struct ceph_inode_info` by 8 bytes on
kernels that have filesystem encryption disabled.

Signed-off-by: Max Kellermann <max.kellermann@xxxxxxxxx>
---
 fs/ceph/inode.c |  8 ++++++--
 fs/ceph/super.h | 11 +++++++++++
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 22c7da1ea61c..1504b889622c 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -680,7 +680,9 @@ struct inode *ceph_alloc_inode(struct super_block *sb)
 	ci->i_truncate_seq = 0;
 	ci->i_truncate_size = 0;
 	ci->i_truncate_pending = 0;
+#ifdef CONFIG_FS_ENCRYPTION
 	ci->i_truncate_pagecache_size = 0;
+#endif
 
 	ci->i_max_size = 0;
 	ci->i_reported_size = 0;
@@ -865,6 +867,7 @@ int ceph_fill_file_size(struct inode *inode, int issued,
 
 		ci->i_truncate_size = truncate_size;
 
+#ifdef CONFIG_FS_ENCRYPTION
 		if (IS_ENCRYPTED(inode)) {
 			doutc(cl, "truncate_pagecache_size %lld -> %llu\n",
 			      ci->i_truncate_pagecache_size, size);
@@ -872,6 +875,7 @@ int ceph_fill_file_size(struct inode *inode, int issued,
 		} else {
 			ci->i_truncate_pagecache_size = truncate_size;
 		}
+#endif
 	}
 	return queue_trunc;
 }
@@ -2331,7 +2335,7 @@ void __ceph_do_pending_vmtruncate(struct inode *inode)
 	/* there should be no reader or writer */
 	WARN_ON_ONCE(ci->i_rd_ref || ci->i_wr_ref);
 
-	to = ci->i_truncate_pagecache_size;
+	to = ceph_get_truncate_pagecache_size(ci);
 	wrbuffer_refs = ci->i_wrbuffer_ref;
 	doutc(cl, "%p %llx.%llx (%d) to %lld\n", inode, ceph_vinop(inode),
 	      ci->i_truncate_pending, to);
@@ -2341,7 +2345,7 @@ void __ceph_do_pending_vmtruncate(struct inode *inode)
 	truncate_pagecache(inode, to);
 
 	spin_lock(&ci->i_ceph_lock);
-	if (to == ci->i_truncate_pagecache_size) {
+	if (to == ceph_get_truncate_pagecache_size(ci)) {
 		ci->i_truncate_pending = 0;
 		finish = 1;
 	}
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index 6aec40955387..f0f03aeb5b19 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -461,11 +461,14 @@ struct ceph_inode_info {
 	u32 i_truncate_seq;        /* last truncate to smaller size */
 	u64 i_truncate_size;       /*  and the size we last truncated down to */
 	int i_truncate_pending;    /*  still need to call vmtruncate */
+
+#ifdef CONFIG_FS_ENCRYPTION
 	/*
 	 * For none fscrypt case it equals to i_truncate_size or it will
 	 * equals to fscrypt_file_size
 	 */
 	u64 i_truncate_pagecache_size;
+#endif
 
 	u64 i_max_size;            /* max file size authorized by mds */
 	u64 i_reported_size; /* (max_)size reported to or requested of mds */
@@ -660,6 +663,14 @@ static inline struct inode *ceph_find_inode(struct super_block *sb,
 	return ilookup5(sb, (unsigned long)vino.ino, ceph_ino_compare, &vino);
 }
 
+static inline u64 ceph_get_truncate_pagecache_size(const struct ceph_inode_info *ci)
+{
+#ifdef CONFIG_CEPH_FS_SNAPSHOTS
+	return ci->i_truncate_pagecache_size;
+#else
+	return ci->i_truncate_size;
+#endif
+}
 
 /*
  * Ceph inode.
-- 
2.47.3