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authorMiklos Szeredi <mszeredi@suse.cz>2014-10-24 00:14:37 +0200
committerMiklos Szeredi <mszeredi@suse.cz>2014-10-24 00:14:37 +0200
commit46fdb794e3f52ef18b859ebc92f0a9d7db21c5df (patch)
tree293f678cfc7e83ee5c901071b0f8fbab11b84c78 /mm
parentcd808deced431b66b5fa4e5c193cb7ec0059eaff (diff)
downloadlinux-sh-46fdb794e3f52ef18b859ebc92f0a9d7db21c5df.tar.gz
shmem: support RENAME_WHITEOUT
Allocate a dentry, initialize it with a whiteout and hash it in the place of the old dentry. Later the old dentry will be moved away and the whiteout will remain. i_mutex protects agains concurrent readdir. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Cc: Hugh Dickins <hughd@google.com>
Diffstat (limited to 'mm')
-rw-r--r--mm/shmem.c36
1 files changed, 35 insertions, 1 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index cd6fc7590e54..185836ba53ef 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2345,6 +2345,32 @@ static int shmem_exchange(struct inode *old_dir, struct dentry *old_dentry, stru
return 0;
}
+static int shmem_whiteout(struct inode *old_dir, struct dentry *old_dentry)
+{
+ struct dentry *whiteout;
+ int error;
+
+ whiteout = d_alloc(old_dentry->d_parent, &old_dentry->d_name);
+ if (!whiteout)
+ return -ENOMEM;
+
+ error = shmem_mknod(old_dir, whiteout,
+ S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
+ dput(whiteout);
+ if (error)
+ return error;
+
+ /*
+ * Cheat and hash the whiteout while the old dentry is still in
+ * place, instead of playing games with FS_RENAME_DOES_D_MOVE.
+ *
+ * d_lookup() will consistently find one of them at this point,
+ * not sure which one, but that isn't even important.
+ */
+ d_rehash(whiteout);
+ return 0;
+}
+
/*
* The VFS layer already does all the dentry stuff for rename,
* we just have to decrement the usage count for the target if
@@ -2356,7 +2382,7 @@ static int shmem_rename2(struct inode *old_dir, struct dentry *old_dentry, struc
struct inode *inode = old_dentry->d_inode;
int they_are_dirs = S_ISDIR(inode->i_mode);
- if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
+ if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
return -EINVAL;
if (flags & RENAME_EXCHANGE)
@@ -2365,6 +2391,14 @@ static int shmem_rename2(struct inode *old_dir, struct dentry *old_dentry, struc
if (!simple_empty(new_dentry))
return -ENOTEMPTY;
+ if (flags & RENAME_WHITEOUT) {
+ int error;
+
+ error = shmem_whiteout(old_dir, old_dentry);
+ if (error)
+ return error;
+ }
+
if (new_dentry->d_inode) {
(void) shmem_unlink(new_dir, new_dentry);
if (they_are_dirs) {