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| author | Miklos Szeredi <mszeredi@suse.cz> | 2014-10-24 00:14:37 +0200 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@suse.cz> | 2014-10-24 00:14:37 +0200 |
| commit | 46fdb794e3f52ef18b859ebc92f0a9d7db21c5df (patch) | |
| tree | 293f678cfc7e83ee5c901071b0f8fbab11b84c78 /mm | |
| parent | cd808deced431b66b5fa4e5c193cb7ec0059eaff (diff) | |
| download | lwn-46fdb794e3f52ef18b859ebc92f0a9d7db21c5df.tar.gz lwn-46fdb794e3f52ef18b859ebc92f0a9d7db21c5df.zip | |
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.c | 36 |
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) { |