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ext4: support RENAME_WHITEOUT
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Add whiteout support to ext4_rename().  A whiteout inode (chrdev/0,0) is
created before the rename takes place.  The whiteout inode is added to the
old entry instead of deleting it.

Signed-off-by: Miklos Szeredi <[email protected]>
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Miklos Szeredi committed Oct 23, 2014
1 parent 0d7a855 commit cd808de
Showing 1 changed file with 78 additions and 17 deletions.
95 changes: 78 additions & 17 deletions fs/ext4/namei.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3190,6 +3190,39 @@ static void ext4_update_dir_count(handle_t *handle, struct ext4_renament *ent)
}
}

static struct inode *ext4_whiteout_for_rename(struct ext4_renament *ent,
int credits, handle_t **h)
{
struct inode *wh;
handle_t *handle;
int retries = 0;

/*
* for inode block, sb block, group summaries,
* and inode bitmap
*/
credits += (EXT4_MAXQUOTAS_TRANS_BLOCKS(ent->dir->i_sb) +
EXT4_XATTR_TRANS_BLOCKS + 4);
retry:
wh = ext4_new_inode_start_handle(ent->dir, S_IFCHR | WHITEOUT_MODE,
&ent->dentry->d_name, 0, NULL,
EXT4_HT_DIR, credits);

handle = ext4_journal_current_handle();
if (IS_ERR(wh)) {
if (handle)
ext4_journal_stop(handle);
if (PTR_ERR(wh) == -ENOSPC &&
ext4_should_retry_alloc(ent->dir->i_sb, &retries))
goto retry;
} else {
*h = handle;
init_special_inode(wh, wh->i_mode, WHITEOUT_DEV);
wh->i_op = &ext4_special_inode_operations;
}
return wh;
}

/*
* Anybody can rename anything with this: the permission checks are left to the
* higher-level routines.
Expand All @@ -3199,7 +3232,8 @@ static void ext4_update_dir_count(handle_t *handle, struct ext4_renament *ent)
* This comes from rename(const char *oldpath, const char *newpath)
*/
static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry)
struct inode *new_dir, struct dentry *new_dentry,
unsigned int flags)
{
handle_t *handle = NULL;
struct ext4_renament old = {
Expand All @@ -3214,6 +3248,9 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
};
int force_reread;
int retval;
struct inode *whiteout = NULL;
int credits;
u8 old_file_type;

dquot_initialize(old.dir);
dquot_initialize(new.dir);
Expand Down Expand Up @@ -3252,11 +3289,17 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
if (new.inode && !test_opt(new.dir->i_sb, NO_AUTO_DA_ALLOC))
ext4_alloc_da_blocks(old.inode);

handle = ext4_journal_start(old.dir, EXT4_HT_DIR,
(2 * EXT4_DATA_TRANS_BLOCKS(old.dir->i_sb) +
EXT4_INDEX_EXTRA_TRANS_BLOCKS + 2));
if (IS_ERR(handle))
return PTR_ERR(handle);
credits = (2 * EXT4_DATA_TRANS_BLOCKS(old.dir->i_sb) +
EXT4_INDEX_EXTRA_TRANS_BLOCKS + 2);
if (!(flags & RENAME_WHITEOUT)) {
handle = ext4_journal_start(old.dir, EXT4_HT_DIR, credits);
if (IS_ERR(handle))
return PTR_ERR(handle);
} else {
whiteout = ext4_whiteout_for_rename(&old, credits, &handle);
if (IS_ERR(whiteout))
return PTR_ERR(whiteout);
}

if (IS_DIRSYNC(old.dir) || IS_DIRSYNC(new.dir))
ext4_handle_sync(handle);
Expand Down Expand Up @@ -3284,13 +3327,26 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
*/
force_reread = (new.dir->i_ino == old.dir->i_ino &&
ext4_test_inode_flag(new.dir, EXT4_INODE_INLINE_DATA));

old_file_type = old.de->file_type;
if (whiteout) {
/*
* Do this before adding a new entry, so the old entry is sure
* to be still pointing to the valid old entry.
*/
retval = ext4_setent(handle, &old, whiteout->i_ino,
EXT4_FT_CHRDEV);
if (retval)
goto end_rename;
ext4_mark_inode_dirty(handle, whiteout);
}
if (!new.bh) {
retval = ext4_add_entry(handle, new.dentry, old.inode);
if (retval)
goto end_rename;
} else {
retval = ext4_setent(handle, &new,
old.inode->i_ino, old.de->file_type);
old.inode->i_ino, old_file_type);
if (retval)
goto end_rename;
}
Expand All @@ -3305,10 +3361,12 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
old.inode->i_ctime = ext4_current_time(old.inode);
ext4_mark_inode_dirty(handle, old.inode);

/*
* ok, that's it
*/
ext4_rename_delete(handle, &old, force_reread);
if (!whiteout) {
/*
* ok, that's it
*/
ext4_rename_delete(handle, &old, force_reread);
}

if (new.inode) {
ext4_dec_count(handle, new.inode);
Expand Down Expand Up @@ -3344,6 +3402,12 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
brelse(old.dir_bh);
brelse(old.bh);
brelse(new.bh);
if (whiteout) {
if (retval)
drop_nlink(whiteout);
unlock_new_inode(whiteout);
iput(whiteout);
}
if (handle)
ext4_journal_stop(handle);
return retval;
Expand Down Expand Up @@ -3476,18 +3540,15 @@ static int ext4_rename2(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry,
unsigned int flags)
{
if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
return -EINVAL;

if (flags & RENAME_EXCHANGE) {
return ext4_cross_rename(old_dir, old_dentry,
new_dir, new_dentry);
}
/*
* Existence checking was done by the VFS, otherwise "RENAME_NOREPLACE"
* is equivalent to regular rename.
*/
return ext4_rename(old_dir, old_dentry, new_dir, new_dentry);

return ext4_rename(old_dir, old_dentry, new_dir, new_dentry, flags);
}

/*
Expand Down

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