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a couple of shmem rename fixes - recent regression from tree-in-dcache 

series and older breakage from stable directory offsets stuff.
 
 Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Merge tag 'pull-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull shmem rename fixes from Al Viro:
 "A couple of shmem rename fixes - recent regression from tree-in-dcache
  series and older breakage from stable directory offsets stuff"

* tag 'pull-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  shmem: fix recovery on rename failures
  shmem_whiteout(): fix regression from tree-in-dcache series
master
Linus Torvalds 2025-12-16 19:44:36 +12:00
parent 53ec4a79ff e1b4c6a583
commit 40fbbd64bb
3 changed files with 39 additions and 51 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

50
fs/libfs.c
View File

@ -346,22 +346,22 @@ void simple_offset_remove(struct offset_ctx *octx, struct dentry *dentry)
* User space expects the directory offset value of the replaced
* (new) directory entry to be unchanged after a rename.
*
* Returns zero on success, a negative errno value on failure.
* Caller must have grabbed a slot for new_dentry in the maple_tree
* associated with new_dir, even if dentry is negative.
*/
int simple_offset_rename(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry)
void simple_offset_rename(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry)
{
struct offset_ctx *old_ctx = old_dir->i_op->get_offset_ctx(old_dir);
struct offset_ctx *new_ctx = new_dir->i_op->get_offset_ctx(new_dir);
long new_offset = dentry2offset(new_dentry);
simple_offset_remove(old_ctx, old_dentry);
if (WARN_ON(!new_offset))
return;
if (new_offset) {
offset_set(new_dentry, 0);
return simple_offset_replace(new_ctx, old_dentry, new_offset);
}
return simple_offset_add(new_ctx, old_dentry);
simple_offset_remove(old_ctx, old_dentry);
offset_set(new_dentry, 0);
WARN_ON(simple_offset_replace(new_ctx, old_dentry, new_offset));
}
/**
@ -388,31 +388,23 @@ int simple_offset_rename_exchange(struct inode *old_dir,
long new_index = dentry2offset(new_dentry);
int ret;
simple_offset_remove(old_ctx, old_dentry);
simple_offset_remove(new_ctx, new_dentry);
if (WARN_ON(!old_index || !new_index))
return -EINVAL;
ret = simple_offset_replace(new_ctx, old_dentry, new_index);
if (ret)
goto out_restore;
ret = mtree_store(&new_ctx->mt, new_index, old_dentry, GFP_KERNEL);
if (WARN_ON(ret))
return ret;
ret = simple_offset_replace(old_ctx, new_dentry, old_index);
if (ret) {
simple_offset_remove(new_ctx, old_dentry);
goto out_restore;
ret = mtree_store(&old_ctx->mt, old_index, new_dentry, GFP_KERNEL);
if (WARN_ON(ret)) {
mtree_store(&new_ctx->mt, new_index, new_dentry, GFP_KERNEL);
return ret;
}
ret = simple_rename_exchange(old_dir, old_dentry, new_dir, new_dentry);
if (ret) {
simple_offset_remove(new_ctx, old_dentry);
simple_offset_remove(old_ctx, new_dentry);
goto out_restore;
}
offset_set(old_dentry, new_index);
offset_set(new_dentry, old_index);
simple_rename_exchange(old_dir, old_dentry, new_dir, new_dentry);
return 0;
out_restore:
(void)simple_offset_replace(old_ctx, old_dentry, old_index);
(void)simple_offset_replace(new_ctx, new_dentry, new_index);
return ret;
}
/**

2
include/linux/fs.h
View File

@ -3247,7 +3247,7 @@ struct offset_ctx {
void simple_offset_init(struct offset_ctx *octx);
int simple_offset_add(struct offset_ctx *octx, struct dentry *dentry);
void simple_offset_remove(struct offset_ctx *octx, struct dentry *dentry);
int simple_offset_rename(struct inode *old_dir, struct dentry *old_dentry,
void simple_offset_rename(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry);
int simple_offset_rename_exchange(struct inode *old_dir,
struct dentry *old_dentry,

38
mm/shmem.c
View File

@ -4019,22 +4019,10 @@ static int shmem_whiteout(struct mnt_idmap *idmap,
whiteout = d_alloc(old_dentry->d_parent, &old_dentry->d_name);
if (!whiteout)
return -ENOMEM;
error = shmem_mknod(idmap, 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;
return error;
}
/*
@ -4050,6 +4038,7 @@ static int shmem_rename2(struct mnt_idmap *idmap,
{
struct inode *inode = d_inode(old_dentry);
int they_are_dirs = S_ISDIR(inode->i_mode);
bool had_offset = false;
int error;
if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
@ -4062,16 +4051,23 @@ static int shmem_rename2(struct mnt_idmap *idmap,
if (!simple_empty(new_dentry))
return -ENOTEMPTY;
if (flags & RENAME_WHITEOUT) {
error = shmem_whiteout(idmap, old_dir, old_dentry);
if (error)
return error;
}
error = simple_offset_rename(old_dir, old_dentry, new_dir, new_dentry);
if (error)
error = simple_offset_add(shmem_get_offset_ctx(new_dir), new_dentry);
if (error == -EBUSY)
had_offset = true;
else if (unlikely(error))
return error;
if (flags & RENAME_WHITEOUT) {
error = shmem_whiteout(idmap, old_dir, old_dentry);
if (error) {
if (!had_offset)
simple_offset_remove(shmem_get_offset_ctx(new_dir),
new_dentry);
return error;
}
}
simple_offset_rename(old_dir, old_dentry, new_dir, new_dentry);
if (d_really_is_positive(new_dentry)) {
(void) shmem_unlink(new_dir, new_dentry);
if (they_are_dirs) {