diff options
Diffstat (limited to 'ext4-Allocate-entire-range-in-zero-range.patch')
| -rw-r--r-- | ext4-Allocate-entire-range-in-zero-range.patch | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/ext4-Allocate-entire-range-in-zero-range.patch b/ext4-Allocate-entire-range-in-zero-range.patch new file mode 100644 index 000000000..3b35e1a1b --- /dev/null +++ b/ext4-Allocate-entire-range-in-zero-range.patch @@ -0,0 +1,78 @@ +From: Lukas Czerner <lczerner@redhat.com> +Date: Wed, 18 Feb 2015 17:49:28 +0100 +Subject: [PATCH] ext4: Allocate entire range in zero range + +Currently there is a bug in zero range code which causes zero range +calls to only allocate block aligned portion of the range, while +ignoring the rest in some cases. + +In some cases, namely if the end of the range is past isize, we do +attempt to preallocate the last nonaligned block. However this might +cause kernel to BUG() in some carefully designed zero range requests on +setups where page size > block size. + +Fix this problem by first preallocating the entire range, including the +nonaligned edges and converting the written extents to unwritten in the +next step. This approach will also give us the advantage of having the +range to be as linearly contiguous as possible. + +Signed-off-by: Lukas Czerner <lczerner@redhat.com> +--- + fs/ext4/extents.c | 31 +++++++++++++++++++------------ + 1 file changed, 19 insertions(+), 12 deletions(-) + +diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c +index bed43081720f..aa522429b751 100644 +--- a/fs/ext4/extents.c ++++ b/fs/ext4/extents.c +@@ -4803,12 +4803,6 @@ static long ext4_zero_range(struct file *file, loff_t offset, + else + max_blocks -= lblk; + +- flags = EXT4_GET_BLOCKS_CREATE_UNWRIT_EXT | +- EXT4_GET_BLOCKS_CONVERT_UNWRITTEN | +- EXT4_EX_NOCACHE; +- if (mode & FALLOC_FL_KEEP_SIZE) +- flags |= EXT4_GET_BLOCKS_KEEP_SIZE; +- + mutex_lock(&inode->i_mutex); + + /* +@@ -4825,15 +4819,28 @@ static long ext4_zero_range(struct file *file, loff_t offset, + ret = inode_newsize_ok(inode, new_size); + if (ret) + goto out_mutex; +- /* +- * If we have a partial block after EOF we have to allocate +- * the entire block. +- */ +- if (partial_end) +- max_blocks += 1; + } + ++ flags = EXT4_GET_BLOCKS_CREATE_UNWRIT_EXT; ++ if (mode & FALLOC_FL_KEEP_SIZE) ++ flags |= EXT4_GET_BLOCKS_KEEP_SIZE; ++ ++ /* Preallocate the range including the unaligned edges */ ++ if (partial_begin || partial_end) { ++ ret = ext4_alloc_file_blocks(file, ++ round_down(offset, 1 << blkbits) >> blkbits, ++ (round_up((offset + len), 1 << blkbits) - ++ round_down(offset, 1 << blkbits)) >> blkbits, ++ new_size, flags, mode); ++ if (ret) ++ goto out_mutex; ++ ++ } ++ ++ /* Zero range excluding the unaligned edges */ + if (max_blocks > 0) { ++ flags |= (EXT4_GET_BLOCKS_CONVERT_UNWRITTEN | ++ EXT4_EX_NOCACHE); + + /* Now release the pages and zero block aligned part of pages*/ + truncate_pagecache_range(inode, start, end - 1); +-- +2.1.0 + |