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[Deepin-Kernel-SIG] [linux 6.6-y] [Upstream] shmem: fix recovery on rename failures #1383

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Merged
opsiff merged 1 commit into from
Dec 17, 2025
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[Deepin-Kernel-SIG] [linux 6.6-y] [Upstream] shmem: fix recovery on rename failures #1383

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40 changes: 15 additions & 25 deletions fs/libfs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -344,22 +344,22 @@ 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
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Copilot AI Dec 17, 2025

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The comment mentions "maple_tree" but the offset_ctx structure in this kernel version uses xarray (xa) not maple_tree. The comment should refer to "xarray" instead to match the actual data structure being used.

Suggested change
* Caller must have grabbed a slot for new_dentry in the maple_tree
* Caller must have grabbed a slot for new_dentry in the xarray

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@Avenger-285714 Avenger-285714 Dec 17, 2025

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The comment mentions "maple_tree" but the offset_ctx structure in this kernel version uses xarray (xa) not maple_tree. The comment should refer to "xarray" instead to match the actual data structure being used.

No.
The linux-stable maintenance policy requires that, when backporting patches, you keep them as close to the original commit as possible — even if the comments no longer match the modified code logic.

* 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));
}

/**
Expand All @@ -386,31 +386,21 @@ int simple_offset_rename_exchange(struct inode *old_dir,
u32 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;
return ret;

ret = simple_offset_replace(old_ctx, new_dentry, old_index);
if (ret) {
simple_offset_remove(new_ctx, old_dentry);
goto out_restore;
simple_offset_replace(new_ctx, new_dentry, new_index);
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;
}
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;
}

/**
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2 changes: 1 addition & 1 deletion include/linux/fs.h
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Original file line number Diff line number Diff line change
Expand Up @@ -3306,7 +3306,7 @@ 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,
Expand Down
18 changes: 13 additions & 5 deletions mm/shmem.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3415,6 +3415,7 @@ 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))
Expand All @@ -3427,16 +3428,23 @@ static int shmem_rename2(struct mnt_idmap *idmap,
if (!simple_empty(new_dentry))
return -ENOTEMPTY;

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 (error) {
if (!had_offset)
simple_offset_remove(shmem_get_offset_ctx(new_dir),
new_dentry);
return error;
}
}

error = simple_offset_rename(old_dir, old_dentry, new_dir, new_dentry);
if (error)
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) {
Expand Down
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