From: Hongzhen Luo <[email protected]>

This patch adds page cache sharing functionality for compressed inodes.

Signed-off-by: Hongzhen Luo <[email protected]>
Signed-off-by: Hongbo Li <[email protected]>
---
 fs/erofs/zdata.c | 37 ++++++++++++++++++++++++-------------
 1 file changed, 24 insertions(+), 13 deletions(-)

diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index 65da21504632..2697c703a4c4 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -493,7 +493,8 @@ enum z_erofs_pclustermode {
 };
 
 struct z_erofs_frontend {
-       struct inode *const inode;
+       struct inode *inode;
+       struct inode *sharedinode;
        struct erofs_map_blocks map;
        struct z_erofs_bvec_iter biter;
 
@@ -508,8 +509,8 @@ struct z_erofs_frontend {
        unsigned int icur;
 };
 
-#define Z_EROFS_DEFINE_FRONTEND(fe, i, ho) struct z_erofs_frontend fe = { \
-       .inode = i, .head = Z_EROFS_PCLUSTER_TAIL, \
+#define Z_EROFS_DEFINE_FRONTEND(fe, i, si, ho) struct z_erofs_frontend fe = { \
+       .inode = i, .sharedinode = si, .head = Z_EROFS_PCLUSTER_TAIL, \
        .mode = Z_EROFS_PCLUSTER_FOLLOWED, .headoffset = ho }
 
 static bool z_erofs_should_alloc_cache(struct z_erofs_frontend *fe)
@@ -1866,7 +1867,7 @@ static void z_erofs_pcluster_readmore(struct 
z_erofs_frontend *f,
                pgoff_t index = cur >> PAGE_SHIFT;
                struct folio *folio;
 
-               folio = erofs_grab_folio_nowait(inode->i_mapping, index);
+               folio = erofs_grab_folio_nowait(f->sharedinode->i_mapping, 
index);
                if (!IS_ERR_OR_NULL(folio)) {
                        if (folio_test_uptodate(folio))
                                folio_unlock(folio);
@@ -1883,8 +1884,10 @@ static void z_erofs_pcluster_readmore(struct 
z_erofs_frontend *f,
 
 static int z_erofs_read_folio(struct file *file, struct folio *folio)
 {
-       struct inode *const inode = folio->mapping->host;
-       Z_EROFS_DEFINE_FRONTEND(f, inode, folio_pos(folio));
+       struct inode *const sharedinode = folio->mapping->host;
+       bool need_iput;
+       struct inode *realinode = erofs_real_inode(sharedinode, &need_iput);
+       Z_EROFS_DEFINE_FRONTEND(f, realinode, sharedinode, folio_pos(folio));
        int err;
 
        trace_erofs_read_folio(folio, false);
@@ -1896,23 +1899,28 @@ static int z_erofs_read_folio(struct file *file, struct 
folio *folio)
        /* if some pclusters are ready, need submit them anyway */
        err = z_erofs_runqueue(&f, 0) ?: err;
        if (err && err != -EINTR)
-               erofs_err(inode->i_sb, "read error %d @ %lu of nid %llu",
-                         err, folio->index, EROFS_I(inode)->nid);
+               erofs_err(realinode->i_sb, "read error %d @ %lu of nid %llu",
+                         err, folio->index, EROFS_I(realinode)->nid);
 
        erofs_put_metabuf(&f.map.buf);
        erofs_release_pages(&f.pagepool);
+
+       if (need_iput)
+               iput(realinode);
        return err;
 }
 
 static void z_erofs_readahead(struct readahead_control *rac)
 {
-       struct inode *const inode = rac->mapping->host;
-       Z_EROFS_DEFINE_FRONTEND(f, inode, readahead_pos(rac));
+       struct inode *const sharedinode = rac->mapping->host;
+       bool need_iput;
+       struct inode *realinode = erofs_real_inode(sharedinode, &need_iput);
+       Z_EROFS_DEFINE_FRONTEND(f, realinode, sharedinode, readahead_pos(rac));
        unsigned int nrpages = readahead_count(rac);
        struct folio *head = NULL, *folio;
        int err;
 
-       trace_erofs_readahead(inode, readahead_index(rac), nrpages, false);
+       trace_erofs_readahead(realinode, readahead_index(rac), nrpages, false);
        z_erofs_pcluster_readmore(&f, rac, true);
        while ((folio = readahead_folio(rac))) {
                folio->private = head;
@@ -1926,8 +1934,8 @@ static void z_erofs_readahead(struct readahead_control 
*rac)
 
                err = z_erofs_scan_folio(&f, folio, true);
                if (err && err != -EINTR)
-                       erofs_err(inode->i_sb, "readahead error at folio %lu @ 
nid %llu",
-                                 folio->index, EROFS_I(inode)->nid);
+                       erofs_err(realinode->i_sb, "readahead error at folio 
%lu @ nid %llu",
+                                 folio->index, EROFS_I(realinode)->nid);
        }
        z_erofs_pcluster_readmore(&f, rac, false);
        z_erofs_pcluster_end(&f);
@@ -1935,6 +1943,9 @@ static void z_erofs_readahead(struct readahead_control 
*rac)
        (void)z_erofs_runqueue(&f, nrpages);
        erofs_put_metabuf(&f.map.buf);
        erofs_release_pages(&f.pagepool);
+
+       if (need_iput)
+               iput(realinode);
 }
 
 const struct address_space_operations z_erofs_aops = {
-- 
2.22.0


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