From: Miklos Szeredi <[email protected]> This adds a new RENAME_WHITEOUT flag. This flag makes rename() create a whiteout of source. The whiteout creation is atomic relative to the rename.
Signed-off-by: Miklos Szeredi <[email protected]> --- fs/ext4/namei.c | 99 ++++++++++++++++++++++++++++++++++++++++--------- fs/namei.c | 8 +++- include/linux/fs.h | 7 ++++ include/uapi/linux/fs.h | 1 + 4 files changed, 95 insertions(+), 20 deletions(-) diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index 1cb84f78909e..f782831b19dc 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -3148,6 +3148,39 @@ 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. @@ -3156,8 +3189,9 @@ static void ext4_update_dir_count(handle_t *handle, struct ext4_renament *ent) * while new_{dentry,inode) refers to the destination dentry/inode * 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) +static int ext4_simple_rename(struct inode *old_dir, struct dentry *old_dentry, + struct inode *new_dir, struct dentry *new_dentry, + unsigned int flags) { handle_t *handle = NULL; struct ext4_renament old = { @@ -3171,6 +3205,9 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry, .inode = new_dentry->d_inode, }; int retval; + struct inode *whiteout = NULL; + int credits; + u8 old_file_type; dquot_initialize(old.dir); dquot_initialize(new.dir); @@ -3202,11 +3239,17 @@ 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); @@ -3225,13 +3268,21 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry, if (retval) goto end_rename; } + old_file_type = old.de->file_type; + if (whiteout) { + 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; } @@ -3243,10 +3294,12 @@ 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); + if (!whiteout) { + /* + * ok, that's it + */ + ext4_rename_delete(handle, &old); + } if (new.inode) { ext4_dec_count(handle, new.inode); @@ -3282,6 +3335,12 @@ end_rename: 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; @@ -3403,22 +3462,26 @@ end_rename: return retval; } +static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry, + struct inode *new_dir, struct dentry *new_dentry) +{ + return ext4_simple_rename(old_dir, old_dentry, new_dir, new_dentry, 0); +} + 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_simple_rename(old_dir, old_dentry, + new_dir, new_dentry, flags); } /* diff --git a/fs/namei.c b/fs/namei.c index 413d7c138e95..adaa73d91173 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -4186,12 +4186,16 @@ SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, bool should_retry = false; int error; - if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE)) + if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) return -EINVAL; - if ((flags & RENAME_NOREPLACE) && (flags & RENAME_EXCHANGE)) + if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && + (flags & RENAME_EXCHANGE)) return -EINVAL; + if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) + return -EPERM; + retry: from = user_path_parent(olddfd, oldname, &oldnd, lookup_flags); if (IS_ERR(from)) { diff --git a/include/linux/fs.h b/include/linux/fs.h index 88ec7a2878bc..48d3bd908b5d 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -228,6 +228,13 @@ typedef void (dio_iodone_t)(struct kiocb *iocb, loff_t offset, #define WHITEOUT_DEV 0 /* + * Whiteout is represented by a char device. The following constants define the + * mode and device number to use. + */ +#define WHITEOUT_MODE 0 +#define WHITEOUT_DEV 0 + +/* * This is the Inode Attributes structure, used for notify_change(). It * uses the above definitions as flags, to know which values have changed. * Also, in this manner, a Filesystem can look at only the values it cares diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h index ca1a11bb4443..3735fa0a6784 100644 --- a/include/uapi/linux/fs.h +++ b/include/uapi/linux/fs.h @@ -37,6 +37,7 @@ #define RENAME_NOREPLACE (1 << 0) /* Don't overwrite target */ #define RENAME_EXCHANGE (1 << 1) /* Exchange source and dest */ +#define RENAME_WHITEOUT (1 << 2) /* Whiteout source */ struct fstrim_range { __u64 start; -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
