Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 22/40] ext4: fix stripe-unaligned allocations | Date | Mon, 6 Nov 2017 10:44:57 +0100 |
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4.4-stable review patch. If anyone has any objections, please let me know.
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From: Jan Kara <jack@suse.cz>
[ Upstream commit d9b22cf9f5466a057f2a4f1e642b469fa9d73117 ]
When a filesystem is created using:
mkfs.ext4 -b 4096 -E stride=512 <dev>
and we try to allocate 64MB extent, we will end up directly in ext4_mb_complex_scan_group(). This is because the request is detected as power-of-two allocation (so we start in ext4_mb_regular_allocator() with ac_criteria == 0) however the check before ext4_mb_simple_scan_group() refuses the direct buddy scan because the allocation request is too large. Since cr == 0, the check whether we should use ext4_mb_scan_aligned() fails as well and we fall back to ext4_mb_complex_scan_group().
Fix the problem by checking for upper limit on power-of-two requests directly when detecting them.
Reported-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Sasha Levin <alexander.levin@verizon.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- fs/ext4/mballoc.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -2136,8 +2136,10 @@ ext4_mb_regular_allocator(struct ext4_al * We search using buddy data only if the order of the request * is greater than equal to the sbi_s_mb_order2_reqs * You can tune it via /sys/fs/ext4/<partition>/mb_order2_req + * We also support searching for power-of-two requests only for + * requests upto maximum buddy size we have constructed. */ - if (i >= sbi->s_mb_order2_reqs) { + if (i >= sbi->s_mb_order2_reqs && i <= sb->s_blocksize_bits + 2) { /* * This should tell if fe_len is exactly power of 2 */ @@ -2207,7 +2209,7 @@ repeat: } ac->ac_groups_scanned++; - if (cr == 0 && ac->ac_2order < sb->s_blocksize_bits+2) + if (cr == 0) ext4_mb_simple_scan_group(ac, &e4b); else if (cr == 1 && sbi->s_stripe && !(ac->ac_g_ex.fe_len % sbi->s_stripe))
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