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fs: replace mmap hook with .mmap_prepare for simple mappings

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Since commit c84bf6dd2b ("mm: introduce new .mmap_prepare() file
callback"), the f_op->mmap() hook has been deprecated in favour of
f_op->mmap_prepare().

This callback is invoked in the mmap() logic far earlier, so error handling
can be performed more safely without complicated and bug-prone state
unwinding required should an error arise.

This hook also avoids passing a pointer to a not-yet-correctly-established
VMA avoiding any issues with referencing this data structure.

It rather provides a pointer to the new struct vm_area_desc descriptor type
which contains all required state and allows easy setting of required
parameters without any consideration needing to be paid to locking or
reference counts.

Note that nested filesystems like overlayfs are compatible with an
.mmap_prepare() callback since commit bb666b7c27 ("mm: add mmap_prepare()
compatibility layer for nested file systems").

In this patch we apply this change to file systems with relatively simple
mmap() hook logic - exfat, ceph, f2fs, bcachefs, zonefs, btrfs, ocfs2,
orangefs, nilfs2, romfs, ramfs and aio.

Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Link: https://lore.kernel.org/f528ac4f35b9378931bd800920fee53fc0c5c74d.1750099179.git.lorenzo.stoakes@oracle.com
Acked-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Lorenzo Stoakes
2025-06-16 20:33:29 +01:00
committed by Christian Brauner
parent 9d5403b103
commit 2e3b37a7e4
16 changed files with 58 additions and 49 deletions
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5
fs/ocfs2/mmap.c
View File

@@ -159,8 +159,9 @@ static const struct vm_operations_struct ocfs2_file_vm_ops = {
.page_mkwrite = ocfs2_page_mkwrite,
};
int ocfs2_mmap(struct file *file, struct vm_area_struct *vma)
int ocfs2_mmap_prepare(struct vm_area_desc *desc)
{
struct file *file = desc->file;
int ret = 0, lock_level = 0;
ret = ocfs2_inode_lock_atime(file_inode(file),
@@ -171,7 +172,7 @@ int ocfs2_mmap(struct file *file, struct vm_area_struct *vma)
}
ocfs2_inode_unlock(file_inode(file), lock_level);
out:
vma->vm_ops = &ocfs2_file_vm_ops;
desc->vm_ops = &ocfs2_file_vm_ops;
return 0;
}