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https://gitee.com/openharmony/third_party_e2fsprogs
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107 lines
3.2 KiB
Diff
107 lines
3.2 KiB
Diff
From 699d448eee4b991acafaae4e4f8222be332d6837 Mon Sep 17 00:00:00 2001
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From: Theodore Ts'o <tytso@mit.edu>
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Date: Thu, 9 Dec 2021 10:55:54 -0500
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Subject: [PATCH] libext2fs: don't old the CACHE_MTX while doing I/O
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A report a deadlock problem caused by I/O errors (caused by e2fsck's
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error handler trying to write to a bad block to perform a forced
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rewrite) uncovered that we were holding the CACHE_MTX while doing read
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operations. This serialized read operations which destroyed the
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performance benefits from doing parallel bitmap loading (or the
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parallel e2fsck processing under development).
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So restructure the code in unix_read_blk64() so that the read is
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always done into the user-provided buffer, and then copied into the
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cache afterwards.
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Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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---
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lib/ext2fs/unix_io.c | 38 +++++++++++++-------------------------
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1 file changed, 13 insertions(+), 25 deletions(-)
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diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
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index 50ac737..e53db33 100644
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--- a/lib/ext2fs/unix_io.c
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+++ b/lib/ext2fs/unix_io.c
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@@ -977,8 +977,8 @@ static errcode_t unix_read_blk64(io_channel channel, unsigned long long block,
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int count, void *buf)
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{
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struct unix_private_data *data;
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- struct unix_cache *cache, *reuse[READ_DIRECT_SIZE];
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- errcode_t retval = 0;
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+ struct unix_cache *cache;
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+ errcode_t retval;
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char *cp;
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int i, j;
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@@ -1005,7 +1005,7 @@ static errcode_t unix_read_blk64(io_channel channel, unsigned long long block,
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mutex_lock(data, CACHE_MTX);
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while (count > 0) {
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/* If it's in the cache, use it! */
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- if ((cache = find_cached_block(data, block, &reuse[0]))) {
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+ if ((cache = find_cached_block(data, block, NULL))) {
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#ifdef DEBUG
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printf("Using cached block %lu\n", block);
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#endif
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@@ -1015,47 +1015,35 @@ static errcode_t unix_read_blk64(io_channel channel, unsigned long long block,
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cp += channel->block_size;
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continue;
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}
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- if (count == 1) {
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- /*
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- * Special case where we read directly into the
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- * cache buffer; important in the O_DIRECT case
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- */
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- cache = reuse[0];
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- reuse_cache(channel, data, cache, block);
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- if ((retval = raw_read_blk(channel, data, block, 1,
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- cache->buf))) {
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- cache->in_use = 0;
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- break;
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- }
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- memcpy(cp, cache->buf, channel->block_size);
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- retval = 0;
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- break;
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- }
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/*
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* Find the number of uncached blocks so we can do a
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* single read request
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*/
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for (i=1; i < count; i++)
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- if (find_cached_block(data, block+i, &reuse[i]))
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+ if (find_cached_block(data, block+i, NULL))
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break;
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#ifdef DEBUG
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printf("Reading %d blocks starting at %lu\n", i, block);
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#endif
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+ mutex_unlock(data, CACHE_MTX);
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if ((retval = raw_read_blk(channel, data, block, i, cp)))
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- break;
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+ return retval;
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+ mutex_lock(data, CACHE_MTX);
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/* Save the results in the cache */
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for (j=0; j < i; j++) {
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+ if (!find_cached_block(data, block, &cache)) {
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+ reuse_cache(channel, data, cache, block);
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+ memcpy(cache->buf, cp, channel->block_size);
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+ }
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count--;
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- cache = reuse[j];
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- reuse_cache(channel, data, cache, block++);
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- memcpy(cache->buf, cp, channel->block_size);
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+ block++;
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cp += channel->block_size;
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}
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}
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mutex_unlock(data, CACHE_MTX);
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- return retval;
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+ return 0;
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#endif /* NO_IO_CACHE */
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}
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--
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1.8.3.1
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