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shmem: Fix shmem_rename2()

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When renaming onto an existing directory entry, user space expects
the replacement entry to have the same directory offset as the
original one.

Link: https://gitlab.alpinelinux.org/alpine/aports/-/issues/15966
Fixes: a2e459555c ("shmem: stable directory offsets")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/r/20240415152057.4605-4-cel@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Chuck Lever
2024-04-15 11:20:56 -04:00
committed by Christian Brauner
parent 5a1a25be99
commit ad191eb6d6
1 changed files with 9 additions and 0 deletions
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9
fs/libfs.c
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@ -366,6 +366,9 @@ int simple_offset_empty(struct dentry *dentry)
* *
* Caller provides appropriate serialization. * Caller provides appropriate serialization.
* *
* 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. * Returns zero on success, a negative errno value on failure.
*/ */
int simple_offset_rename(struct inode *old_dir, struct dentry *old_dentry, int simple_offset_rename(struct inode *old_dir, struct dentry *old_dentry,
@ -373,8 +376,14 @@ int simple_offset_rename(struct inode *old_dir, struct dentry *old_dentry,
{ {
struct offset_ctx *old_ctx = old_dir->i_op->get_offset_ctx(old_dir); 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); 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); simple_offset_remove(old_ctx, old_dentry);
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); return simple_offset_add(new_ctx, old_dentry);
} }