[PATCH-v4 7/7] btrfs: add an is_readonly() so btrfs can use common code for update_time()

Theodore Ts'o
2014-11-26T10:24:09Z

The only reason btrfs cloned code from the VFS layer was so it could
add a check to see if a subvolume is read-ony. Instead of doing that,
let's add a new inode operation which allows a file system to return
an error if the inode is read-only, and use that in update_time().
There may be other places where the VFS layer may want to know that
btrfs would want to treat an inode is read-only.

With this commit, there are no remaining users of update_time() in the
inode operations structure, so we can remove it and simply things
further.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: linux-btrfs@vger.kernel.org
Reviewed-by: David Sterba <dsterba@suse.cz>
---
fs/btrfs/inode.c | 26 ++++++--------------------
fs/inode.c | 22 +++++++++++-----------
include/linux/fs.h | 2 +-
3 files changed, 18 insertions(+), 32 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index a5e0d0d..0bfe3a4 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5554,26 +5554,12 @@ static int btrfs_dirty_inode(struct inode *inode)
return ret;
}

-/*
- * This is a copy of file_update_time. We need this so we can return error on
- * ENOSPC for updating the inode in the case of file write and mmap writes.
- */
-static int btrfs_update_time(struct inode *inode, struct timespec *now,
- int flags)
+static int btrfs_is_readonly(struct inode *inode)
{
struct btrfs_root *root = BTRFS_I(inode)->root;

if (btrfs_root_readonly(root))
return -EROFS;
-
- if (flags & S_VERSION)
- inode_inc_iversion(inode);
- if (flags & S_CTIME)
- inode->i_ctime = *now;
- if (flags & S_MTIME)
- inode->i_mtime = *now;
- if (flags & S_ATIME)
- inode->i_atime = *now;
return 0;
}

@@ -9466,8 +9452,8 @@ static const struct inode_operations btrfs_dir_inode_operations = {
.permission = btrfs_permission,
.get_acl = btrfs_get_acl,
.set_acl = btrfs_set_acl,
- .update_time = btrfs_update_time,
.write_time = btrfs_write_time,
+ .is_readonly = btrfs_is_readonly,
.tmpfile = btrfs_tmpfile,
};
static const struct inode_operations btrfs_dir_ro_inode_operations = {
@@ -9475,8 +9461,8 @@ static const struct inode_operations btrfs_dir_ro_inode_operations = {
.permission = btrfs_permission,
.get_acl = btrfs_get_acl,
.set_acl = btrfs_set_acl,
- .update_time = btrfs_update_time,
.write_time = btrfs_write_time,
+ .is_readonly = btrfs_is_readonly,
};

static const struct file_operations btrfs_dir_file_operations = {
@@ -9546,8 +9532,8 @@ static const struct inode_operations btrfs_file_inode_operations = {
.fiemap = btrfs_fiemap,
.get_acl = btrfs_get_acl,
.set_acl = btrfs_set_acl,
- .update_time = btrfs_update_time,
.write_time = btrfs_write_time,
+ .is_readonly = btrfs_is_readonly,
};
static const struct inode_operations btrfs_special_inode_operations = {
.getattr = btrfs_getattr,
@@ -9559,8 +9545,8 @@ static const struct inode_operations btrfs_special_inode_operations = {
.removexattr = btrfs_removexattr,
.get_acl = btrfs_get_acl,
.set_acl = btrfs_set_acl,
- .update_time = btrfs_update_time,
.write_time = btrfs_write_time,
+ .is_readonly = btrfs_is_readonly,
};
static const struct inode_operations btrfs_symlink_inode_operations = {
.readlink = generic_readlink,
@@ -9573,8 +9559,8 @@ static const struct inode_operations btrfs_symlink_inode_operations = {
.getxattr = btrfs_getxattr,
.listxattr = btrfs_listxattr,
.removexattr = btrfs_removexattr,
- .update_time = btrfs_update_time,
.write_time = btrfs_write_time,
+ .is_readonly = btrfs_is_readonly,
};

const struct dentry_operations btrfs_dentry_operations = {
diff --git a/fs/inode.c b/fs/inode.c
index 0b4c6ae..e29bd2d 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1554,20 +1554,20 @@ static int update_time(struct inode *inode, struct timespec *time, int flags)
unsigned short days_since_boot;
int ret;

- if (inode->i_op->update_time) {
- ret = inode->i_op->update_time(inode, time, flags);
+ if (inode->i_op->is_readonly) {
+ ret = inode->i_op->is_readonly(inode);
if (ret)
return ret;
- } else {
- if (flags & S_ATIME)
- inode->i_atime = *time;
- if (flags & S_VERSION)
- inode_inc_iversion(inode);
- if (flags & S_CTIME)
- inode->i_ctime = *time;
- if (flags & S_MTIME)
- inode->i_mtime = *time;
}
+ if (flags & S_ATIME)
+ inode->i_atime = *time;
+ if (flags & S_VERSION)
+ inode_inc_iversion(inode);
+ if (flags & S_CTIME)
+ inode->i_ctime = *time;
+ if (flags & S_MTIME)
+ inode->i_mtime = *time;
+
/*
* If i_ts_dirty_day is zero, then either we have not deferred
* timestamp updates, or the system has been up for less than
diff --git a/include/linux/fs.h b/include/linux/fs.h
index dc615ec..6e41107 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1545,8 +1545,8 @@ struct inode_operations {
int (*removexattr) (struct dentry *, const char *);
int (*fiemap)(struct inode *, struct fiemap_extent_info *, u64 start,
u64 len);
- int (*update_time)(struct inode *, struct timespec *, int);
int (*write_time)(struct inode *);
+ int (*is_readonly)(struct inode *);
int (*atomic_open)(struct inode *, struct dentry *,
struct file *, unsigned open_flag,
umode_t create_mode, int *opened);
--
2.1.0