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OpenCloudOS-Kernel/fs/squashfs/page_actor.h

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treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 499 Based on 1 normalized pattern(s): this work is licensed under the terms of the gnu gpl version 2 see the copying file in the top level directory extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 35 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Enrico Weigelt <info@metux.net> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190604081206.797835076@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-04 16:11:32 +08:00
/* SPDX-License-Identifier: GPL-2.0-only */
Squashfs: Generalise paging handling in the decompressors Further generalise the decompressors by adding a page handler abstraction. This adds helpers to allow the decompressors to access and process the output buffers in an implementation independant manner. This allows different types of output buffer to be passed to the decompressors, with the implementation specific aspects handled at decompression time, but without the knowledge being held in the decompressor wrapper code. This will allow the decompressors to handle Squashfs cache buffers, and page cache pages. This patch adds the abstraction and an implementation for the caches. Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Reviewed-by: Minchan Kim <minchan@kernel.org>
2013-11-18 10:59:12 +08:00
#ifndef PAGE_ACTOR_H
#define PAGE_ACTOR_H
/*
* Copyright (c) 2013
* Phillip Lougher <phillip@squashfs.org.uk>
*/
Squashfs: Directly decompress into the page cache for file data This introduces an implementation of squashfs_readpage_block() that directly decompresses into the page cache. This uses the previously added page handler abstraction to push down the necessary kmap_atomic/kunmap_atomic operations on the page cache buffers into the decompressors. This enables direct copying into the page cache without using the slow kmap/kunmap calls. The code detects when multiple threads are racing in squashfs_readpage() to decompress the same block, and avoids this regression by falling back to using an intermediate buffer. This patch enhances the performance of Squashfs significantly when multiple processes are accessing the filesystem simultaneously because it not only reduces memcopying, but it more importantly eliminates the lock contention on the intermediate buffer. Using single-thread decompression. dd if=file1 of=/dev/null bs=4096 & dd if=file2 of=/dev/null bs=4096 & dd if=file3 of=/dev/null bs=4096 & dd if=file4 of=/dev/null bs=4096 Before: 629145600 bytes (629 MB) copied, 45.8046 s, 13.7 MB/s After: 629145600 bytes (629 MB) copied, 9.29414 s, 67.7 MB/s Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Reviewed-by: Minchan Kim <minchan@kernel.org>
2013-11-13 10:04:19 +08:00
struct squashfs_page_actor {
union {
void **buffer;
struct page **page;
};
void *pageaddr;
squashfs: extend "page actor" to handle missing pages Patch series "Squashfs: handle missing pages decompressing into page cache". This patchset enables Squashfs to handle missing pages when directly decompressing datablocks into the page cache. Previously if the full set of pages needed was not available, Squashfs would have to fall back to using an intermediate buffer (the older method), which is slower, involving a memcopy, and it introduces contention on a shared buffer. The first patch extends the "page actor" code to handle missing pages. The second patch updates Squashfs_readpage_block() to use the new functionality, and removes the code that falls back to using an intermediate buffer. This patchset is independent of the readahead work, and it is standalone. It can be merged on its own. But the readahead patch for efficiency also needs this patch-set. This patch (of 2): This patch extends the "page actor" code to handle missing pages. Previously if the full set of pages needed to decompress a Squashfs datablock was unavailable, this would cause decompression to fail on the missing pages. In this case direct decompression into the page cache could not be achieved and the code would fall back to using the older intermediate buffer method. With this patch, direct decompression into the page cache can be achieved with missing pages. For "multi-shot" decompressors (zlib, xz, zstd), the page actor will allocate a temporary buffer which is passed to the decompressor, and then freed by the page actor. For "single shot" decompressors (lz4, lzo) which decompress into a contiguous "bounce buffer", and which is then copied into the page cache, it would be pointless to allocate a temporary buffer, memcpy into it, and then free it. For these decompressors -ENOMEM is returned, which signifies that the memcpy for that page should be skipped. This also happens if the data block is uncompressed. Link: https://lkml.kernel.org/r/20220611032133.5743-1-phillip@squashfs.org.uk Link: https://lkml.kernel.org/r/20220611032133.5743-2-phillip@squashfs.org.uk Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Hsin-Yi Wang <hsinyi@chromium.org> Cc: Xiongwei Song <Xiongwei.Song@windriver.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-06-11 11:21:32 +08:00
void *tmp_buffer;
Squashfs: Directly decompress into the page cache for file data This introduces an implementation of squashfs_readpage_block() that directly decompresses into the page cache. This uses the previously added page handler abstraction to push down the necessary kmap_atomic/kunmap_atomic operations on the page cache buffers into the decompressors. This enables direct copying into the page cache without using the slow kmap/kunmap calls. The code detects when multiple threads are racing in squashfs_readpage() to decompress the same block, and avoids this regression by falling back to using an intermediate buffer. This patch enhances the performance of Squashfs significantly when multiple processes are accessing the filesystem simultaneously because it not only reduces memcopying, but it more importantly eliminates the lock contention on the intermediate buffer. Using single-thread decompression. dd if=file1 of=/dev/null bs=4096 & dd if=file2 of=/dev/null bs=4096 & dd if=file3 of=/dev/null bs=4096 & dd if=file4 of=/dev/null bs=4096 Before: 629145600 bytes (629 MB) copied, 45.8046 s, 13.7 MB/s After: 629145600 bytes (629 MB) copied, 9.29414 s, 67.7 MB/s Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Reviewed-by: Minchan Kim <minchan@kernel.org>
2013-11-13 10:04:19 +08:00
void *(*squashfs_first_page)(struct squashfs_page_actor *);
void *(*squashfs_next_page)(struct squashfs_page_actor *);
void (*squashfs_finish_page)(struct squashfs_page_actor *);
squashfs: fix read regression introduced in readahead code Patch series "squashfs: fix some regressions introduced in the readahead code". This patchset fixes 3 regressions introduced by the recent readahead code changes. The first regression is causing "snaps" to randomly fail after a couple of hours or days, which how the regression came to light. This patch (of 3): If a file isn't a whole multiple of the page size, the last page will have trailing bytes unfilled. There was a mistake in the readahead code which did this. In particular it incorrectly assumed that the last page in the readahead page array (page[nr_pages - 1]) will always contain the last page in the block, which if we're at file end, will be the page that needs to be zero filled. But the readahead code may not return the last page in the block, which means it is unmapped and will be skipped by the decompressors (a temporary buffer used). In this case the zero filling code will zero out the wrong page, leading to data corruption. Fix this by by extending the "page actor" to return the last page if present, or NULL if a temporary buffer was used. Link: https://lkml.kernel.org/r/20221020223616.7571-1-phillip@squashfs.org.uk Link: https://lkml.kernel.org/r/20221020223616.7571-2-phillip@squashfs.org.uk Fixes: 8fc78b6fe24c ("squashfs: implement readahead") Link: https://lore.kernel.org/lkml/b0c258c3-6dcf-aade-efc4-d62a8b3a1ce2@alu.unizg.hr/ Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Reported-by: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr> Tested-by: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr> Tested-by: Slade Watkins <srw@sladewatkins.net> Tested-by: Bagas Sanjaya <bagasdotme@gmail.com> Reported-by: Marc Miltenberger <marcmiltenberger@gmail.com> Cc: Dimitri John Ledkov <dimitri.ledkov@canonical.com> Cc: Hsin-Yi Wang <hsinyi@chromium.org> Cc: Thorsten Leemhuis <regressions@leemhuis.info> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-10-21 06:36:14 +08:00
struct page *last_page;
Squashfs: Directly decompress into the page cache for file data This introduces an implementation of squashfs_readpage_block() that directly decompresses into the page cache. This uses the previously added page handler abstraction to push down the necessary kmap_atomic/kunmap_atomic operations on the page cache buffers into the decompressors. This enables direct copying into the page cache without using the slow kmap/kunmap calls. The code detects when multiple threads are racing in squashfs_readpage() to decompress the same block, and avoids this regression by falling back to using an intermediate buffer. This patch enhances the performance of Squashfs significantly when multiple processes are accessing the filesystem simultaneously because it not only reduces memcopying, but it more importantly eliminates the lock contention on the intermediate buffer. Using single-thread decompression. dd if=file1 of=/dev/null bs=4096 & dd if=file2 of=/dev/null bs=4096 & dd if=file3 of=/dev/null bs=4096 & dd if=file4 of=/dev/null bs=4096 Before: 629145600 bytes (629 MB) copied, 45.8046 s, 13.7 MB/s After: 629145600 bytes (629 MB) copied, 9.29414 s, 67.7 MB/s Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Reviewed-by: Minchan Kim <minchan@kernel.org>
2013-11-13 10:04:19 +08:00
int pages;
int length;
int next_page;
squashfs: extend "page actor" to handle missing pages Patch series "Squashfs: handle missing pages decompressing into page cache". This patchset enables Squashfs to handle missing pages when directly decompressing datablocks into the page cache. Previously if the full set of pages needed was not available, Squashfs would have to fall back to using an intermediate buffer (the older method), which is slower, involving a memcopy, and it introduces contention on a shared buffer. The first patch extends the "page actor" code to handle missing pages. The second patch updates Squashfs_readpage_block() to use the new functionality, and removes the code that falls back to using an intermediate buffer. This patchset is independent of the readahead work, and it is standalone. It can be merged on its own. But the readahead patch for efficiency also needs this patch-set. This patch (of 2): This patch extends the "page actor" code to handle missing pages. Previously if the full set of pages needed to decompress a Squashfs datablock was unavailable, this would cause decompression to fail on the missing pages. In this case direct decompression into the page cache could not be achieved and the code would fall back to using the older intermediate buffer method. With this patch, direct decompression into the page cache can be achieved with missing pages. For "multi-shot" decompressors (zlib, xz, zstd), the page actor will allocate a temporary buffer which is passed to the decompressor, and then freed by the page actor. For "single shot" decompressors (lz4, lzo) which decompress into a contiguous "bounce buffer", and which is then copied into the page cache, it would be pointless to allocate a temporary buffer, memcpy into it, and then free it. For these decompressors -ENOMEM is returned, which signifies that the memcpy for that page should be skipped. This also happens if the data block is uncompressed. Link: https://lkml.kernel.org/r/20220611032133.5743-1-phillip@squashfs.org.uk Link: https://lkml.kernel.org/r/20220611032133.5743-2-phillip@squashfs.org.uk Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Hsin-Yi Wang <hsinyi@chromium.org> Cc: Xiongwei Song <Xiongwei.Song@windriver.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-06-11 11:21:32 +08:00
int alloc_buffer;
int returned_pages;
pgoff_t next_index;
Squashfs: Directly decompress into the page cache for file data This introduces an implementation of squashfs_readpage_block() that directly decompresses into the page cache. This uses the previously added page handler abstraction to push down the necessary kmap_atomic/kunmap_atomic operations on the page cache buffers into the decompressors. This enables direct copying into the page cache without using the slow kmap/kunmap calls. The code detects when multiple threads are racing in squashfs_readpage() to decompress the same block, and avoids this regression by falling back to using an intermediate buffer. This patch enhances the performance of Squashfs significantly when multiple processes are accessing the filesystem simultaneously because it not only reduces memcopying, but it more importantly eliminates the lock contention on the intermediate buffer. Using single-thread decompression. dd if=file1 of=/dev/null bs=4096 & dd if=file2 of=/dev/null bs=4096 & dd if=file3 of=/dev/null bs=4096 & dd if=file4 of=/dev/null bs=4096 Before: 629145600 bytes (629 MB) copied, 45.8046 s, 13.7 MB/s After: 629145600 bytes (629 MB) copied, 9.29414 s, 67.7 MB/s Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Reviewed-by: Minchan Kim <minchan@kernel.org>
2013-11-13 10:04:19 +08:00
};
squashfs: extend "page actor" to handle missing pages Patch series "Squashfs: handle missing pages decompressing into page cache". This patchset enables Squashfs to handle missing pages when directly decompressing datablocks into the page cache. Previously if the full set of pages needed was not available, Squashfs would have to fall back to using an intermediate buffer (the older method), which is slower, involving a memcopy, and it introduces contention on a shared buffer. The first patch extends the "page actor" code to handle missing pages. The second patch updates Squashfs_readpage_block() to use the new functionality, and removes the code that falls back to using an intermediate buffer. This patchset is independent of the readahead work, and it is standalone. It can be merged on its own. But the readahead patch for efficiency also needs this patch-set. This patch (of 2): This patch extends the "page actor" code to handle missing pages. Previously if the full set of pages needed to decompress a Squashfs datablock was unavailable, this would cause decompression to fail on the missing pages. In this case direct decompression into the page cache could not be achieved and the code would fall back to using the older intermediate buffer method. With this patch, direct decompression into the page cache can be achieved with missing pages. For "multi-shot" decompressors (zlib, xz, zstd), the page actor will allocate a temporary buffer which is passed to the decompressor, and then freed by the page actor. For "single shot" decompressors (lz4, lzo) which decompress into a contiguous "bounce buffer", and which is then copied into the page cache, it would be pointless to allocate a temporary buffer, memcpy into it, and then free it. For these decompressors -ENOMEM is returned, which signifies that the memcpy for that page should be skipped. This also happens if the data block is uncompressed. Link: https://lkml.kernel.org/r/20220611032133.5743-1-phillip@squashfs.org.uk Link: https://lkml.kernel.org/r/20220611032133.5743-2-phillip@squashfs.org.uk Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Hsin-Yi Wang <hsinyi@chromium.org> Cc: Xiongwei Song <Xiongwei.Song@windriver.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-06-11 11:21:32 +08:00
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);
squashfs: fix read regression introduced in readahead code Patch series "squashfs: fix some regressions introduced in the readahead code". This patchset fixes 3 regressions introduced by the recent readahead code changes. The first regression is causing "snaps" to randomly fail after a couple of hours or days, which how the regression came to light. This patch (of 3): If a file isn't a whole multiple of the page size, the last page will have trailing bytes unfilled. There was a mistake in the readahead code which did this. In particular it incorrectly assumed that the last page in the readahead page array (page[nr_pages - 1]) will always contain the last page in the block, which if we're at file end, will be the page that needs to be zero filled. But the readahead code may not return the last page in the block, which means it is unmapped and will be skipped by the decompressors (a temporary buffer used). In this case the zero filling code will zero out the wrong page, leading to data corruption. Fix this by by extending the "page actor" to return the last page if present, or NULL if a temporary buffer was used. Link: https://lkml.kernel.org/r/20221020223616.7571-1-phillip@squashfs.org.uk Link: https://lkml.kernel.org/r/20221020223616.7571-2-phillip@squashfs.org.uk Fixes: 8fc78b6fe24c ("squashfs: implement readahead") Link: https://lore.kernel.org/lkml/b0c258c3-6dcf-aade-efc4-d62a8b3a1ce2@alu.unizg.hr/ Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Reported-by: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr> Tested-by: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr> Tested-by: Slade Watkins <srw@sladewatkins.net> Tested-by: Bagas Sanjaya <bagasdotme@gmail.com> Reported-by: Marc Miltenberger <marcmiltenberger@gmail.com> Cc: Dimitri John Ledkov <dimitri.ledkov@canonical.com> Cc: Hsin-Yi Wang <hsinyi@chromium.org> Cc: Thorsten Leemhuis <regressions@leemhuis.info> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-10-21 06:36:14 +08:00
static inline struct page *squashfs_page_actor_free(struct squashfs_page_actor *actor)
squashfs: don't call kmalloc in decompressors The decompressors may be called while in an atomic section. So move the kmalloc() out of this path, and into the "page actor" init function. This fixes a regression introduced by commit f268eedddf35 ("squashfs: extend "page actor" to handle missing pages") Link: https://lkml.kernel.org/r/20220822215430.15933-1-phillip@squashfs.org.uk Fixes: f268eedddf35 ("squashfs: extend "page actor" to handle missing pages") Reported-by: Chris Murphy <lists@colorremedies.com> Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-08-23 05:54:30 +08:00
{
squashfs: fix read regression introduced in readahead code Patch series "squashfs: fix some regressions introduced in the readahead code". This patchset fixes 3 regressions introduced by the recent readahead code changes. The first regression is causing "snaps" to randomly fail after a couple of hours or days, which how the regression came to light. This patch (of 3): If a file isn't a whole multiple of the page size, the last page will have trailing bytes unfilled. There was a mistake in the readahead code which did this. In particular it incorrectly assumed that the last page in the readahead page array (page[nr_pages - 1]) will always contain the last page in the block, which if we're at file end, will be the page that needs to be zero filled. But the readahead code may not return the last page in the block, which means it is unmapped and will be skipped by the decompressors (a temporary buffer used). In this case the zero filling code will zero out the wrong page, leading to data corruption. Fix this by by extending the "page actor" to return the last page if present, or NULL if a temporary buffer was used. Link: https://lkml.kernel.org/r/20221020223616.7571-1-phillip@squashfs.org.uk Link: https://lkml.kernel.org/r/20221020223616.7571-2-phillip@squashfs.org.uk Fixes: 8fc78b6fe24c ("squashfs: implement readahead") Link: https://lore.kernel.org/lkml/b0c258c3-6dcf-aade-efc4-d62a8b3a1ce2@alu.unizg.hr/ Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Reported-by: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr> Tested-by: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr> Tested-by: Slade Watkins <srw@sladewatkins.net> Tested-by: Bagas Sanjaya <bagasdotme@gmail.com> Reported-by: Marc Miltenberger <marcmiltenberger@gmail.com> Cc: Dimitri John Ledkov <dimitri.ledkov@canonical.com> Cc: Hsin-Yi Wang <hsinyi@chromium.org> Cc: Thorsten Leemhuis <regressions@leemhuis.info> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-10-21 06:36:14 +08:00
struct page *last_page = actor->last_page;
squashfs: don't call kmalloc in decompressors The decompressors may be called while in an atomic section. So move the kmalloc() out of this path, and into the "page actor" init function. This fixes a regression introduced by commit f268eedddf35 ("squashfs: extend "page actor" to handle missing pages") Link: https://lkml.kernel.org/r/20220822215430.15933-1-phillip@squashfs.org.uk Fixes: f268eedddf35 ("squashfs: extend "page actor" to handle missing pages") Reported-by: Chris Murphy <lists@colorremedies.com> Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-08-23 05:54:30 +08:00
kfree(actor->tmp_buffer);
kfree(actor);
squashfs: fix read regression introduced in readahead code Patch series "squashfs: fix some regressions introduced in the readahead code". This patchset fixes 3 regressions introduced by the recent readahead code changes. The first regression is causing "snaps" to randomly fail after a couple of hours or days, which how the regression came to light. This patch (of 3): If a file isn't a whole multiple of the page size, the last page will have trailing bytes unfilled. There was a mistake in the readahead code which did this. In particular it incorrectly assumed that the last page in the readahead page array (page[nr_pages - 1]) will always contain the last page in the block, which if we're at file end, will be the page that needs to be zero filled. But the readahead code may not return the last page in the block, which means it is unmapped and will be skipped by the decompressors (a temporary buffer used). In this case the zero filling code will zero out the wrong page, leading to data corruption. Fix this by by extending the "page actor" to return the last page if present, or NULL if a temporary buffer was used. Link: https://lkml.kernel.org/r/20221020223616.7571-1-phillip@squashfs.org.uk Link: https://lkml.kernel.org/r/20221020223616.7571-2-phillip@squashfs.org.uk Fixes: 8fc78b6fe24c ("squashfs: implement readahead") Link: https://lore.kernel.org/lkml/b0c258c3-6dcf-aade-efc4-d62a8b3a1ce2@alu.unizg.hr/ Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Reported-by: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr> Tested-by: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr> Tested-by: Slade Watkins <srw@sladewatkins.net> Tested-by: Bagas Sanjaya <bagasdotme@gmail.com> Reported-by: Marc Miltenberger <marcmiltenberger@gmail.com> Cc: Dimitri John Ledkov <dimitri.ledkov@canonical.com> Cc: Hsin-Yi Wang <hsinyi@chromium.org> Cc: Thorsten Leemhuis <regressions@leemhuis.info> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-10-21 06:36:14 +08:00
return last_page;
squashfs: don't call kmalloc in decompressors The decompressors may be called while in an atomic section. So move the kmalloc() out of this path, and into the "page actor" init function. This fixes a regression introduced by commit f268eedddf35 ("squashfs: extend "page actor" to handle missing pages") Link: https://lkml.kernel.org/r/20220822215430.15933-1-phillip@squashfs.org.uk Fixes: f268eedddf35 ("squashfs: extend "page actor" to handle missing pages") Reported-by: Chris Murphy <lists@colorremedies.com> Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-08-23 05:54:30 +08:00
}
Squashfs: Directly decompress into the page cache for file data This introduces an implementation of squashfs_readpage_block() that directly decompresses into the page cache. This uses the previously added page handler abstraction to push down the necessary kmap_atomic/kunmap_atomic operations on the page cache buffers into the decompressors. This enables direct copying into the page cache without using the slow kmap/kunmap calls. The code detects when multiple threads are racing in squashfs_readpage() to decompress the same block, and avoids this regression by falling back to using an intermediate buffer. This patch enhances the performance of Squashfs significantly when multiple processes are accessing the filesystem simultaneously because it not only reduces memcopying, but it more importantly eliminates the lock contention on the intermediate buffer. Using single-thread decompression. dd if=file1 of=/dev/null bs=4096 & dd if=file2 of=/dev/null bs=4096 & dd if=file3 of=/dev/null bs=4096 & dd if=file4 of=/dev/null bs=4096 Before: 629145600 bytes (629 MB) copied, 45.8046 s, 13.7 MB/s After: 629145600 bytes (629 MB) copied, 9.29414 s, 67.7 MB/s Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Reviewed-by: Minchan Kim <minchan@kernel.org>
2013-11-13 10:04:19 +08:00
static inline void *squashfs_first_page(struct squashfs_page_actor *actor)
{
return actor->squashfs_first_page(actor);
}
static inline void *squashfs_next_page(struct squashfs_page_actor *actor)
{
return actor->squashfs_next_page(actor);
}
static inline void squashfs_finish_page(struct squashfs_page_actor *actor)
{
actor->squashfs_finish_page(actor);
}
squashfs: extend "page actor" to handle missing pages Patch series "Squashfs: handle missing pages decompressing into page cache". This patchset enables Squashfs to handle missing pages when directly decompressing datablocks into the page cache. Previously if the full set of pages needed was not available, Squashfs would have to fall back to using an intermediate buffer (the older method), which is slower, involving a memcopy, and it introduces contention on a shared buffer. The first patch extends the "page actor" code to handle missing pages. The second patch updates Squashfs_readpage_block() to use the new functionality, and removes the code that falls back to using an intermediate buffer. This patchset is independent of the readahead work, and it is standalone. It can be merged on its own. But the readahead patch for efficiency also needs this patch-set. This patch (of 2): This patch extends the "page actor" code to handle missing pages. Previously if the full set of pages needed to decompress a Squashfs datablock was unavailable, this would cause decompression to fail on the missing pages. In this case direct decompression into the page cache could not be achieved and the code would fall back to using the older intermediate buffer method. With this patch, direct decompression into the page cache can be achieved with missing pages. For "multi-shot" decompressors (zlib, xz, zstd), the page actor will allocate a temporary buffer which is passed to the decompressor, and then freed by the page actor. For "single shot" decompressors (lz4, lzo) which decompress into a contiguous "bounce buffer", and which is then copied into the page cache, it would be pointless to allocate a temporary buffer, memcpy into it, and then free it. For these decompressors -ENOMEM is returned, which signifies that the memcpy for that page should be skipped. This also happens if the data block is uncompressed. Link: https://lkml.kernel.org/r/20220611032133.5743-1-phillip@squashfs.org.uk Link: https://lkml.kernel.org/r/20220611032133.5743-2-phillip@squashfs.org.uk Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Hsin-Yi Wang <hsinyi@chromium.org> Cc: Xiongwei Song <Xiongwei.Song@windriver.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-06-11 11:21:32 +08:00
static inline void squashfs_actor_nobuff(struct squashfs_page_actor *actor)
{
actor->alloc_buffer = 0;
}
Squashfs: Directly decompress into the page cache for file data This introduces an implementation of squashfs_readpage_block() that directly decompresses into the page cache. This uses the previously added page handler abstraction to push down the necessary kmap_atomic/kunmap_atomic operations on the page cache buffers into the decompressors. This enables direct copying into the page cache without using the slow kmap/kunmap calls. The code detects when multiple threads are racing in squashfs_readpage() to decompress the same block, and avoids this regression by falling back to using an intermediate buffer. This patch enhances the performance of Squashfs significantly when multiple processes are accessing the filesystem simultaneously because it not only reduces memcopying, but it more importantly eliminates the lock contention on the intermediate buffer. Using single-thread decompression. dd if=file1 of=/dev/null bs=4096 & dd if=file2 of=/dev/null bs=4096 & dd if=file3 of=/dev/null bs=4096 & dd if=file4 of=/dev/null bs=4096 Before: 629145600 bytes (629 MB) copied, 45.8046 s, 13.7 MB/s After: 629145600 bytes (629 MB) copied, 9.29414 s, 67.7 MB/s Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Reviewed-by: Minchan Kim <minchan@kernel.org>
2013-11-13 10:04:19 +08:00
#endif