Before the update_time inode operation was indroduced, it was
not possible to prevent updates of atime on RO subvolumes.
btrfs_update_time does now check if the root is RO and skip
updating of atime.
This patch requires the update_time patches from Josef
Bacik.
Signed-off-by: Alexander Block <abloc...@googlemail.com>
---
fs/btrfs/inode.c | 26 +++++++++++++++++++++-----
fs/inode.c | 3 +++
2 files changed, 24 insertions(+), 5 deletions(-)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 54ae3df..b48db5a 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4470,14 +4470,30 @@ int btrfs_dirty_inode(struct inode *inode)
static int btrfs_update_time(struct inode *inode, struct timespec *now,
int flags)
{
- if (flags & S_VERSION)
+ struct btrfs_root *root = BTRFS_I(inode)->root;
+ int did_update = 0;
+
+ if (flags & S_VERSION) {
inode_inc_iversion(inode);
- if (flags & S_CTIME)
+ did_update = 1;
+ }
+ if (flags & S_CTIME) {
inode->i_ctime = *now;
- if (flags & S_MTIME)
+ did_update = 1;
+ }
+ if (flags & S_MTIME) {
inode->i_mtime = *now;
- if (flags & S_ATIME)
- inode->i_atime = *now;
+ did_update = 1;
+ }
+ if (flags & S_ATIME) {
+ /* don't do atime updates on RO subvolumes */
+ if (!btrfs_root_readonly(root)) {
+ inode->i_atime = *now;
+ did_update = 1;
+ }
+ }
+ if (!did_update)
+ return 0;
return btrfs_dirty_inode(inode);
}
diff --git a/fs/inode.c b/fs/inode.c
index 06d8bd4..949d06f 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1545,6 +1545,9 @@ void touch_atime(struct path *path)
* Btrfs), but since we touch atime while walking down the path we
* really don't care if we failed to update the atime of the file,
* so just ignore the return value.
+ * Also, the checks done above to see if updating atime is allowed
+ * are not enough for some filesystems. Btrfs for example may have
+ * RO subvolumes on a RW filesystems, which vfs is not aware of.
*/
update_time(inode, &now, S_ATIME);
mnt_drop_write(mnt);
--
1.7.10
--
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