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Merge patch series "Squashfs: Update code to not use page->index"
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Phillip Lougher <phillip@squashfs.org.uk> says:

In the near future page->index will be removed [1].  Any code which
still uses page->index needs to be updated.

This patch-set contains 4 patches which updates most of the code in
Squashfs.  The exceptions are functions which have been fixed in
recent patches [2] & [3].

[1]: https://lore.kernel.org/all/Zp8fgUSIBGQ1TN0D@casper.infradead.org/
[2]: https://lore.kernel.org/all/20240817101146.2347378-1-lizetao1@huawei.com/
[3]: https://lore.kernel.org/all/20240817101146.2347378-2-lizetao1@huawei.com/

* patchesf from https://lore.kernel.org/r/20240818235847.170468-1-phillip@squashfs.org.uk:
  Squashfs: Rewrite and update squashfs_readahead_fragment() to not use page->index
  Squashfs: Update squashfs_readpage_block() to not use page->index
  Squashfs: Update squashfs_readahead() to not use page->index
  Squashfs: Update page_actor to not use page->index

Link: https://lore.kernel.org/r/20240818235847.170468-1-phillip@squashfs.org.uk
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Christian Brauner committed Aug 19, 2024
2 parents 424f8cb + fd54fa6 commit d937c81
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Showing 4 changed files with 76 additions and 39 deletions.
84 changes: 57 additions & 27 deletions fs/squashfs/file.c
Original file line number Diff line number Diff line change
Expand Up @@ -494,39 +494,73 @@ static int squashfs_read_folio(struct file *file, struct folio *folio)
}

static int squashfs_readahead_fragment(struct page **page,
unsigned int pages, unsigned int expected)
unsigned int pages, unsigned int expected, loff_t start)
{
struct inode *inode = page[0]->mapping->host;
struct squashfs_cache_entry *buffer = squashfs_get_fragment(inode->i_sb,
squashfs_i(inode)->fragment_block,
squashfs_i(inode)->fragment_size);
struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
unsigned int n, mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1;
int error = buffer->error;
int i, bytes, copied;
struct squashfs_page_actor *actor;
unsigned int offset;
void *addr;
struct page *last_page;

if (buffer->error)
goto out;

if (error)
actor = squashfs_page_actor_init_special(msblk, page, pages,
expected, start);
if (!actor)
goto out;

expected += squashfs_i(inode)->fragment_offset;
squashfs_actor_nobuff(actor);
addr = squashfs_first_page(actor);

for (copied = offset = 0; offset < expected; offset += PAGE_SIZE) {
int avail = min_t(int, expected - offset, PAGE_SIZE);

if (!IS_ERR(addr)) {
bytes = squashfs_copy_data(addr, buffer, offset +
squashfs_i(inode)->fragment_offset, avail);

if (bytes != avail)
goto failed;
}

copied += avail;
addr = squashfs_next_page(actor);
}

for (n = 0; n < pages; n++) {
unsigned int base = (page[n]->index & mask) << PAGE_SHIFT;
unsigned int offset = base + squashfs_i(inode)->fragment_offset;
last_page = squashfs_page_actor_free(actor);

if (expected > offset) {
unsigned int avail = min_t(unsigned int, expected -
offset, PAGE_SIZE);
if (copied == expected) {
/* Last page (if present) may have trailing bytes not filled */
bytes = copied % PAGE_SIZE;
if (bytes && last_page)
memzero_page(last_page, bytes, PAGE_SIZE - bytes);

squashfs_fill_page(page[n], buffer, offset, avail);
for (i = 0; i < pages; i++) {
flush_dcache_page(page[i]);
SetPageUptodate(page[i]);
}
}

unlock_page(page[n]);
put_page(page[n]);
for (i = 0; i < pages; i++) {
unlock_page(page[i]);
put_page(page[i]);
}

squashfs_cache_put(buffer);
return 0;

failed:
squashfs_page_actor_free(actor);

out:
squashfs_cache_put(buffer);
return error;
return 1;
}

static void squashfs_readahead(struct readahead_control *ractl)
Expand All @@ -551,7 +585,6 @@ static void squashfs_readahead(struct readahead_control *ractl)
return;

for (;;) {
pgoff_t index;
int res, bsize;
u64 block = 0;
unsigned int expected;
Expand All @@ -570,26 +603,21 @@ static void squashfs_readahead(struct readahead_control *ractl)
if (readahead_pos(ractl) >= i_size_read(inode))
goto skip_pages;

index = pages[0]->index >> shift;

if ((pages[nr_pages - 1]->index >> shift) != index)
goto skip_pages;

if (index == file_end && squashfs_i(inode)->fragment_block !=
SQUASHFS_INVALID_BLK) {
if (start >> msblk->block_log == file_end &&
squashfs_i(inode)->fragment_block != SQUASHFS_INVALID_BLK) {
res = squashfs_readahead_fragment(pages, nr_pages,
expected);
expected, start);
if (res)
goto skip_pages;
continue;
}

bsize = read_blocklist(inode, index, &block);
bsize = read_blocklist(inode, start >> msblk->block_log, &block);
if (bsize == 0)
goto skip_pages;

actor = squashfs_page_actor_init_special(msblk, pages, nr_pages,
expected);
expected, start);
if (!actor)
goto skip_pages;

Expand All @@ -602,7 +630,7 @@ static void squashfs_readahead(struct readahead_control *ractl)

/* Last page (if present) may have trailing bytes not filled */
bytes = res % PAGE_SIZE;
if (index == file_end && bytes && last_page)
if (start >> msblk->block_log == file_end && bytes && last_page)
memzero_page(last_page, bytes,
PAGE_SIZE - bytes);

Expand All @@ -616,6 +644,8 @@ static void squashfs_readahead(struct readahead_control *ractl)
unlock_page(pages[i]);
put_page(pages[i]);
}

start += readahead_batch_length(ractl);
}

kfree(pages);
Expand Down
17 changes: 9 additions & 8 deletions fs/squashfs/file_direct.c
Original file line number Diff line number Diff line change
Expand Up @@ -23,15 +23,15 @@ int squashfs_readpage_block(struct page *target_page, u64 block, int bsize,
int expected)

{
struct folio *folio = page_folio(target_page);
struct inode *inode = target_page->mapping->host;
struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;

loff_t file_end = (i_size_read(inode) - 1) >> PAGE_SHIFT;
int mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1;
loff_t start_index = target_page->index & ~mask;
loff_t start_index = folio->index & ~mask;
loff_t end_index = start_index | mask;
int i, n, pages, bytes, res = -ENOMEM;
struct page **page;
struct page **page, *last_page;
struct squashfs_page_actor *actor;
void *pageaddr;

Expand All @@ -46,7 +46,7 @@ int squashfs_readpage_block(struct page *target_page, u64 block, int bsize,

/* Try to grab all the pages covered by the Squashfs block */
for (i = 0, n = start_index; n <= end_index; n++) {
page[i] = (n == target_page->index) ? target_page :
page[i] = (n == folio->index) ? target_page :
grab_cache_page_nowait(target_page->mapping, n);

if (page[i] == NULL)
Expand All @@ -67,14 +67,15 @@ int squashfs_readpage_block(struct page *target_page, u64 block, int bsize,
* Create a "page actor" which will kmap and kunmap the
* page cache pages appropriately within the decompressor
*/
actor = squashfs_page_actor_init_special(msblk, page, pages, expected);
actor = squashfs_page_actor_init_special(msblk, page, pages, expected,
start_index << PAGE_SHIFT);
if (actor == NULL)
goto out;

/* Decompress directly into the page cache buffers */
res = squashfs_read_data(inode->i_sb, block, bsize, NULL, actor);

squashfs_page_actor_free(actor);
last_page = squashfs_page_actor_free(actor);

if (res < 0)
goto mark_errored;
Expand All @@ -86,8 +87,8 @@ int squashfs_readpage_block(struct page *target_page, u64 block, int bsize,

/* Last page (if present) may have trailing bytes not filled */
bytes = res % PAGE_SIZE;
if (page[pages - 1]->index == end_index && bytes) {
pageaddr = kmap_local_page(page[pages - 1]);
if (end_index == file_end && last_page && bytes) {
pageaddr = kmap_local_page(last_page);
memset(pageaddr + bytes, 0, PAGE_SIZE - bytes);
kunmap_local(pageaddr);
}
Expand Down
11 changes: 8 additions & 3 deletions fs/squashfs/page_actor.c
Original file line number Diff line number Diff line change
Expand Up @@ -60,6 +60,11 @@ struct squashfs_page_actor *squashfs_page_actor_init(void **buffer,
}

/* Implementation of page_actor for decompressing directly into page cache. */
static loff_t page_next_index(struct squashfs_page_actor *actor)
{
return page_folio(actor->page[actor->next_page])->index;
}

static void *handle_next_page(struct squashfs_page_actor *actor)
{
int max_pages = (actor->length + PAGE_SIZE - 1) >> PAGE_SHIFT;
Expand All @@ -68,7 +73,7 @@ static void *handle_next_page(struct squashfs_page_actor *actor)
return NULL;

if ((actor->next_page == actor->pages) ||
(actor->next_index != actor->page[actor->next_page]->index)) {
(actor->next_index != page_next_index(actor))) {
actor->next_index++;
actor->returned_pages++;
actor->last_page = NULL;
Expand Down Expand Up @@ -103,7 +108,7 @@ static void direct_finish_page(struct squashfs_page_actor *actor)
}

struct squashfs_page_actor *squashfs_page_actor_init_special(struct squashfs_sb_info *msblk,
struct page **page, int pages, int length)
struct page **page, int pages, int length, loff_t start_index)
{
struct squashfs_page_actor *actor = kmalloc(sizeof(*actor), GFP_KERNEL);

Expand All @@ -125,7 +130,7 @@ struct squashfs_page_actor *squashfs_page_actor_init_special(struct squashfs_sb_
actor->pages = pages;
actor->next_page = 0;
actor->returned_pages = 0;
actor->next_index = page[0]->index & ~((1 << (msblk->block_log - PAGE_SHIFT)) - 1);
actor->next_index = start_index >> PAGE_SHIFT;
actor->pageaddr = NULL;
actor->last_page = NULL;
actor->alloc_buffer = msblk->decompressor->alloc_buffer;
Expand Down
3 changes: 2 additions & 1 deletion fs/squashfs/page_actor.h
Original file line number Diff line number Diff line change
Expand Up @@ -29,7 +29,8 @@ extern struct squashfs_page_actor *squashfs_page_actor_init(void **buffer,
int pages, int length);
extern struct squashfs_page_actor *squashfs_page_actor_init_special(
struct squashfs_sb_info *msblk,
struct page **page, int pages, int length);
struct page **page, int pages, int length,
loff_t start_index);
static inline struct page *squashfs_page_actor_free(struct squashfs_page_actor *actor)
{
struct page *last_page = actor->last_page;
Expand Down

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