[PATCH 3/4] erofs: tidy up zdata.c

Gao Xiang
2025-01-14T03:44:42Z

All small code style adjustments, no logic changes:

- z_erofs_decompress_frontend => z_erofs_frontend;
- z_erofs_decompress_backend => z_erofs_backend;
- Use Z_EROFS_DEFINE_FRONTEND() to replace DECOMPRESS_FRONTEND_INIT();
- `nr_folios` should be `nrpages` in z_erofs_readahead();
- Refine in-line comments.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
fs/erofs/zdata.c | 111 ++++++++++++++++++-----------------------------
1 file changed, 43 insertions(+), 68 deletions(-)

diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index 8bafc4d9edbe..dcbb692ac058 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -455,31 +455,25 @@ int __init z_erofs_init_subsystem(void)
}

enum z_erofs_pclustermode {
+ /* It has previously been linked into another processing chain */
Z_EROFS_PCLUSTER_INFLIGHT,
/*
- * a weak form of Z_EROFS_PCLUSTER_FOLLOWED, the difference is that it
- * could be dispatched into bypass queue later due to uptodated managed
- * pages. All related online pages cannot be reused for inplace I/O (or
- * bvpage) since it can be directly decoded without I/O submission.
+ * A weaker form of Z_EROFS_PCLUSTER_FOLLOWED; the difference is that it
+ * may be dispatched to the bypass queue later due to uptodated managed
+ * folios. All file-backed folios related to this pcluster cannot be
+ * reused for in-place I/O (or bvpage) since the pcluster may be decoded
+ * in a separate queue (and thus out of order).
*/
Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE,
/*
- * The pcluster was just linked to a decompression chain by us. It can
- * also be linked with the remaining pclusters, which means if the
- * processing page is the tail page of a pcluster, this pcluster can
- * safely use the whole page (since the previous pcluster is within the
- * same chain) for in-place I/O, as illustrated below:
- * ___________________________________________________
- * | tail (partial) page | head (partial) page |
- * | (of the current pcl) | (of the previous pcl) |
- * |___PCLUSTER_FOLLOWED___|_____PCLUSTER_FOLLOWED_____|
- *
- * [ (*) the page above can be used as inplace I/O. ]
+ * The pcluster has just been linked to our processing chain.
+ * File-backed folios (except for the head page) related to it can be
+ * used for in-place I/O (or bvpage).
*/
Z_EROFS_PCLUSTER_FOLLOWED,
};

-struct z_erofs_decompress_frontend {
+struct z_erofs_frontend {
struct inode *const inode;
struct erofs_map_blocks map;
struct z_erofs_bvec_iter biter;
@@ -495,11 +489,11 @@ struct z_erofs_decompress_frontend {
unsigned int icur;
};

-#define DECOMPRESS_FRONTEND_INIT(__i) { \
- .inode = __i, .head = Z_EROFS_PCLUSTER_TAIL, \
- .mode = Z_EROFS_PCLUSTER_FOLLOWED }
+#define Z_EROFS_DEFINE_FRONTEND(fe, i, ho) struct z_erofs_frontend fe = { \
+ .inode = i, .head = Z_EROFS_PCLUSTER_TAIL, \
+ .mode = Z_EROFS_PCLUSTER_FOLLOWED, .headoffset = ho }

-static bool z_erofs_should_alloc_cache(struct z_erofs_decompress_frontend *fe)
+static bool z_erofs_should_alloc_cache(struct z_erofs_frontend *fe)
{
unsigned int cachestrategy = EROFS_I_SB(fe->inode)->opt.cache_strategy;

@@ -516,7 +510,7 @@ static bool z_erofs_should_alloc_cache(struct z_erofs_decompress_frontend *fe)
return false;
}

-static void z_erofs_bind_cache(struct z_erofs_decompress_frontend *fe)
+static void z_erofs_bind_cache(struct z_erofs_frontend *fe)
{
struct address_space *mc = MNGD_MAPPING(EROFS_I_SB(fe->inode));
struct z_erofs_pcluster *pcl = fe->pcl;
@@ -673,7 +667,7 @@ int erofs_init_managed_cache(struct super_block *sb)
}

/* callers must be with pcluster lock held */
-static int z_erofs_attach_page(struct z_erofs_decompress_frontend *fe,
+static int z_erofs_attach_page(struct z_erofs_frontend *fe,
struct z_erofs_bvec *bvec, bool exclusive)
{
struct z_erofs_pcluster *pcl = fe->pcl;
@@ -719,7 +713,7 @@ static bool z_erofs_get_pcluster(struct z_erofs_pcluster *pcl)
return true;
}

-static int z_erofs_register_pcluster(struct z_erofs_decompress_frontend *fe)
+static int z_erofs_register_pcluster(struct z_erofs_frontend *fe)
{
struct erofs_map_blocks *map = &fe->map;
struct super_block *sb = fe->inode->i_sb;
@@ -789,7 +783,7 @@ static int z_erofs_register_pcluster(struct z_erofs_decompress_frontend *fe)
return err;
}

-static int z_erofs_pcluster_begin(struct z_erofs_decompress_frontend *fe)
+static int z_erofs_pcluster_begin(struct z_erofs_frontend *fe)
{
struct erofs_map_blocks *map = &fe->map;
struct super_block *sb = fe->inode->i_sb;
@@ -862,14 +856,9 @@ static int z_erofs_pcluster_begin(struct z_erofs_decompress_frontend *fe)
return 0;
}

-/*
- * keep in mind that no referenced pclusters will be freed
- * only after a RCU grace period.
- */
static void z_erofs_rcu_callback(struct rcu_head *head)
{
- z_erofs_free_pcluster(container_of(head,
- struct z_erofs_pcluster, rcu));
+ z_erofs_free_pcluster(container_of(head, struct z_erofs_pcluster, rcu));
}

static bool __erofs_try_to_release_pcluster(struct erofs_sb_info *sbi,
@@ -911,8 +900,7 @@ static bool erofs_try_to_release_pcluster(struct erofs_sb_info *sbi,
return free;
}

-unsigned long z_erofs_shrink_scan(struct erofs_sb_info *sbi,
- unsigned long nr_shrink)
+unsigned long z_erofs_shrink_scan(struct erofs_sb_info *sbi, unsigned long nr)
{
struct z_erofs_pcluster *pcl;
unsigned int freed = 0;
@@ -926,7 +914,7 @@ unsigned long z_erofs_shrink_scan(struct erofs_sb_info *sbi,
xa_unlock(&sbi->managed_pslots);

++freed;
- if (!--nr_shrink)
+ if (!--nr)
return freed;
xa_lock(&sbi->managed_pslots);
}
@@ -955,7 +943,7 @@ static void z_erofs_put_pcluster(struct erofs_sb_info *sbi,
call_rcu(&pcl->rcu, z_erofs_rcu_callback);
}

-static void z_erofs_pcluster_end(struct z_erofs_decompress_frontend *fe)
+static void z_erofs_pcluster_end(struct z_erofs_frontend *fe)
{
struct z_erofs_pcluster *pcl = fe->pcl;

@@ -968,13 +956,9 @@ static void z_erofs_pcluster_end(struct z_erofs_decompress_frontend *fe)
if (fe->candidate_bvpage)
fe->candidate_bvpage = NULL;

- /*
- * if all pending pages are added, don't hold its reference
- * any longer if the pcluster isn't hosted by ourselves.
- */
+ /* Drop refcount if it doesn't belong to our processing chain */
if (fe->mode < Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE)
z_erofs_put_pcluster(EROFS_I_SB(fe->inode), pcl, false);
-
fe->pcl = NULL;
}

@@ -1003,7 +987,7 @@ static int z_erofs_read_fragment(struct super_block *sb, struct folio *folio,
return 0;
}

-static int z_erofs_scan_folio(struct z_erofs_decompress_frontend *f,
+static int z_erofs_scan_folio(struct z_erofs_frontend *f,
struct folio *folio, bool ra)
{
struct inode *const inode = f->inode;
@@ -1118,7 +1102,7 @@ static bool z_erofs_page_is_invalidated(struct page *page)
return !page_folio(page)->mapping && !z_erofs_is_shortlived_page(page);
}

-struct z_erofs_decompress_backend {
+struct z_erofs_backend {
struct page *onstack_pages[Z_EROFS_ONSTACK_PAGES];
struct super_block *sb;
struct z_erofs_pcluster *pcl;
@@ -1138,7 +1122,7 @@ struct z_erofs_bvec_item {
struct list_head list;
};

-static void z_erofs_do_decompressed_bvec(struct z_erofs_decompress_backend *be,
+static void z_erofs_do_decompressed_bvec(struct z_erofs_backend *be,
struct z_erofs_bvec *bvec)
{
struct z_erofs_bvec_item *item;
@@ -1161,8 +1145,7 @@ static void z_erofs_do_decompressed_bvec(struct z_erofs_decompress_backend *be,
list_add(&item->list, &be->decompressed_secondary_bvecs);
}

-static void z_erofs_fill_other_copies(struct z_erofs_decompress_backend *be,
- int err)
+static void z_erofs_fill_other_copies(struct z_erofs_backend *be, int err)
{
unsigned int off0 = be->pcl->pageofs_out;
struct list_head *p, *n;
@@ -1203,7 +1186,7 @@ static void z_erofs_fill_other_copies(struct z_erofs_decompress_backend *be,
}
}

-static void z_erofs_parse_out_bvecs(struct z_erofs_decompress_backend *be)
+static void z_erofs_parse_out_bvecs(struct z_erofs_backend *be)
{
struct z_erofs_pcluster *pcl = be->pcl;
struct z_erofs_bvec_iter biter;
@@ -1228,8 +1211,7 @@ static void z_erofs_parse_out_bvecs(struct z_erofs_decompress_backend *be)
z_erofs_put_shortlivedpage(be->pagepool, old_bvpage);
}

-static int z_erofs_parse_in_bvecs(struct z_erofs_decompress_backend *be,
- bool *overlapped)
+static int z_erofs_parse_in_bvecs(struct z_erofs_backend *be, bool *overlapped)
{
struct z_erofs_pcluster *pcl = be->pcl;
unsigned int pclusterpages = z_erofs_pclusterpages(pcl);
@@ -1264,8 +1246,7 @@ static int z_erofs_parse_in_bvecs(struct z_erofs_decompress_backend *be,
return err;
}

-static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be,
- int err)
+static int z_erofs_decompress_pcluster(struct z_erofs_backend *be, int err)
{
struct erofs_sb_info *const sbi = EROFS_SB(be->sb);
struct z_erofs_pcluster *pcl = be->pcl;
@@ -1395,7 +1376,7 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be,
static int z_erofs_decompress_queue(const struct z_erofs_decompressqueue *io,
struct page **pagepool)
{
- struct z_erofs_decompress_backend be = {
+ struct z_erofs_backend be = {
.sb = io->sb,
.pagepool = pagepool,
.decompressed_secondary_bvecs =
@@ -1473,7 +1454,7 @@ static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io,
}

static void z_erofs_fill_bio_vec(struct bio_vec *bvec,
- struct z_erofs_decompress_frontend *f,
+ struct z_erofs_frontend *f,
struct z_erofs_pcluster *pcl,
unsigned int nr,
struct address_space *mc)
@@ -1652,7 +1633,7 @@ static void z_erofs_endio(struct bio *bio)
bio_put(bio);
}

-static void z_erofs_submit_queue(struct z_erofs_decompress_frontend *f,
+static void z_erofs_submit_queue(struct z_erofs_frontend *f,
struct z_erofs_decompressqueue *fgq,
bool *force_fg, bool readahead)
{
@@ -1785,17 +1766,16 @@ static void z_erofs_submit_queue(struct z_erofs_decompress_frontend *f,
z_erofs_decompress_kickoff(q[JQ_SUBMIT], nr_bios);
}

-static int z_erofs_runqueue(struct z_erofs_decompress_frontend *f,
- unsigned int ra_folios)
+static int z_erofs_runqueue(struct z_erofs_frontend *f, unsigned int rapages)
{
struct z_erofs_decompressqueue io[NR_JOBQUEUES];
struct erofs_sb_info *sbi = EROFS_I_SB(f->inode);
- bool force_fg = z_erofs_is_sync_decompress(sbi, ra_folios);
+ bool force_fg = z_erofs_is_sync_decompress(sbi, rapages);
int err;

if (f->head == Z_EROFS_PCLUSTER_TAIL)
return 0;
- z_erofs_submit_queue(f, io, &force_fg, !!ra_folios);
+ z_erofs_submit_queue(f, io, &force_fg, !!rapages);

/* handle bypass queue (no i/o pclusters) immediately */
err = z_erofs_decompress_queue(&io[JQ_BYPASS], &f->pagepool);
@@ -1813,7 +1793,7 @@ static int z_erofs_runqueue(struct z_erofs_decompress_frontend *f,
* Since partial uptodate is still unimplemented for now, we have to use
* approximate readmore strategies as a start.
*/
-static void z_erofs_pcluster_readmore(struct z_erofs_decompress_frontend *f,
+static void z_erofs_pcluster_readmore(struct z_erofs_frontend *f,
struct readahead_control *rac, bool backmost)
{
struct inode *inode = f->inode;
@@ -1868,12 +1848,10 @@ static void z_erofs_pcluster_readmore(struct z_erofs_decompress_frontend *f,
static int z_erofs_read_folio(struct file *file, struct folio *folio)
{
struct inode *const inode = folio->mapping->host;
- struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
+ Z_EROFS_DEFINE_FRONTEND(f, inode, folio_pos(folio));
int err;

trace_erofs_read_folio(folio, false);
- f.headoffset = (erofs_off_t)folio->index << PAGE_SHIFT;
-
z_erofs_pcluster_readmore(&f, NULL, true);
err = z_erofs_scan_folio(&f, folio, false);
z_erofs_pcluster_readmore(&f, NULL, false);
@@ -1893,17 +1871,14 @@ static int z_erofs_read_folio(struct file *file, struct folio *folio)
static void z_erofs_readahead(struct readahead_control *rac)
{
struct inode *const inode = rac->mapping->host;
- struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
+ Z_EROFS_DEFINE_FRONTEND(f, inode, readahead_pos(rac));
struct folio *head = NULL, *folio;
- unsigned int nr_folios;
+ unsigned int nrpages = readahead_count(rac);
int err;

- f.headoffset = readahead_pos(rac);
-
z_erofs_pcluster_readmore(&f, rac, true);
- nr_folios = readahead_count(rac);
- trace_erofs_readpages(inode, readahead_index(rac), nr_folios, false);
-
+ nrpages = readahead_count(rac);
+ trace_erofs_readpages(inode, readahead_index(rac), nrpages, false);
while ((folio = readahead_folio(rac))) {
folio->private = head;
head = folio;
@@ -1922,7 +1897,7 @@ static void z_erofs_readahead(struct readahead_control *rac)
z_erofs_pcluster_readmore(&f, rac, false);
z_erofs_pcluster_end(&f);

- (void)z_erofs_runqueue(&f, nr_folios);
+ (void)z_erofs_runqueue(&f, nrpages);
erofs_put_metabuf(&f.map.buf);
erofs_release_pages(&f.pagepool);
}
--
2.43.5