On 2025/11/14 17:55, Hongbo Li wrote:
From: Hongzhen Luo <[email protected]>
Currently, reading files with different paths (or names) but the same
content will consume multiple copies of the page cache, even if the
content of these page caches is the same. For example, reading
identical files (e.g., *.so files) from two different minor versions of
container images will cost multiple copies of the same page cache,
since different containers have different mount points. Therefore,
sharing the page cache for files with the same content can save memory.
This introduces the page cache share feature in erofs. It allocate a
deduplicated inode and use its page cache as shared. Reads for files
with identical content will ultimately be routed to the page cache of
the deduplicated inode. In this way, a single page cache satisfies
multiple read requests for different files with the same contents.
Signed-off-by: Hongzhen Luo <[email protected]>
Signed-off-by: Hongbo Li <[email protected]>
---
...
+
+static int erofs_ishare_file_open(struct inode *inode, struct file *file)
+{
+ struct file *realfile;
+ struct inode *dedup;
+
+ dedup = EROFS_I(inode)->ishare;
+ if (!dedup)
+ return -EINVAL;
+
+ realfile = alloc_file_pseudo(dedup, erofs_ishare_mnt,
"erofs_ishare_file",
+ O_RDONLY, &erofs_file_fops);
+ if (IS_ERR(realfile))
+ return PTR_ERR(realfile);
+
+ file_ra_state_init(&realfile->f_ra, file->f_mapping);
+ realfile->private_data = EROFS_I(inode);
+ file->private_data = realfile;
+ return 0;
Again, as Amir mentioned before, it should be converted to use (at least)
some of backing file interfaces, please see:
file_user_path() and file_user_inode() in include/linux/fs.h
Or are you sure /proc/<pid>/maps is shown as expected?
Thanks,
Gao Xiang
