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authorRoman Gushchin <guro@fb.com>2020-02-29 03:14:11 +0300
committerTheodore Ts'o <tytso@mit.edu>2020-04-16 06:58:48 +0300
commitd87f639258a6a5980183f11876c884931ad93da2 (patch)
treef840887fbe136455b2eb47710c222018352f566c /fs
parentc2a559bc0e7ed5a715ad6b947025b33cb7c05ea7 (diff)
downloadlinux-d87f639258a6a5980183f11876c884931ad93da2.tar.xz
ext4: use non-movable memory for superblock readahead
Since commit a8ac900b8163 ("ext4: use non-movable memory for the superblock") buffers for ext4 superblock were allocated using the sb_bread_unmovable() helper which allocated buffer heads out of non-movable memory blocks. It was necessarily to not block page migrations and do not cause cma allocation failures. However commit 85c8f176a611 ("ext4: preload block group descriptors") broke this by introducing pre-reading of the ext4 superblock. The problem is that __breadahead() is using __getblk() underneath, which allocates buffer heads out of movable memory. It resulted in page migration failures I've seen on a machine with an ext4 partition and a preallocated cma area. Fix this by introducing sb_breadahead_unmovable() and __breadahead_gfp() helpers which use non-movable memory for buffer head allocations and use them for the ext4 superblock readahead. Reviewed-by: Andreas Dilger <adilger@dilger.ca> Fixes: 85c8f176a611 ("ext4: preload block group descriptors") Signed-off-by: Roman Gushchin <guro@fb.com> Link: https://lore.kernel.org/r/20200229001411.128010-1-guro@fb.com Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs')
-rw-r--r--fs/buffer.c11
-rw-r--r--fs/ext4/inode.c2
-rw-r--r--fs/ext4/super.c2
3 files changed, 13 insertions, 2 deletions
diff --git a/fs/buffer.c b/fs/buffer.c
index f73276d746bb..599a0bf7257b 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1371,6 +1371,17 @@ void __breadahead(struct block_device *bdev, sector_t block, unsigned size)
}
EXPORT_SYMBOL(__breadahead);
+void __breadahead_gfp(struct block_device *bdev, sector_t block, unsigned size,
+ gfp_t gfp)
+{
+ struct buffer_head *bh = __getblk_gfp(bdev, block, size, gfp);
+ if (likely(bh)) {
+ ll_rw_block(REQ_OP_READ, REQ_RAHEAD, 1, &bh);
+ brelse(bh);
+ }
+}
+EXPORT_SYMBOL(__breadahead_gfp);
+
/**
* __bread_gfp() - reads a specified block and returns the bh
* @bdev: the block_device to read from
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 68f6c0af8e5d..2a4aae6acdcb 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4364,7 +4364,7 @@ make_io:
if (end > table)
end = table;
while (b <= end)
- sb_breadahead(sb, b++);
+ sb_breadahead_unmovable(sb, b++);
}
/*
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 9728e7b0e84f..83413f0f1e28 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4340,7 +4340,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
/* Pre-read the descriptors into the buffer cache */
for (i = 0; i < db_count; i++) {
block = descriptor_loc(sb, logical_sb_block, i);
- sb_breadahead(sb, block);
+ sb_breadahead_unmovable(sb, block);
}
for (i = 0; i < db_count; i++) {