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btrfs: scrub: add memalloc_nofs protection around init_ipath
init_ipath is called from a safe ioctl context and from scrub when printing an error. The protection is added for three reasons: * init_data_container calls vmalloc and this does not work as expected in the GFP_NOFS context, so this silently does GFP_KERNEL and might deadlock in some cases * keep the context constraint of GFP_NOFS, used by scrub * we want to use GFP_KERNEL unconditionally inside init_ipath or its callees Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: David Sterba <dsterba@suse.com>
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1 changed files with 9 additions and 0 deletions
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@ -18,6 +18,7 @@
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#include <linux/blkdev.h>
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#include <linux/ratelimit.h>
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#include <linux/sched/mm.h>
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#include "ctree.h"
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#include "volumes.h"
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#include "disk-io.h"
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@ -733,6 +734,7 @@ static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root,
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u32 nlink;
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int ret;
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int i;
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unsigned nofs_flag;
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struct extent_buffer *eb;
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struct btrfs_inode_item *inode_item;
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struct scrub_warning *swarn = warn_ctx;
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@ -771,7 +773,14 @@ static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root,
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nlink = btrfs_inode_nlink(eb, inode_item);
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btrfs_release_path(swarn->path);
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/*
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* init_path might indirectly call vmalloc, or use GFP_KERNEL. Scrub
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* uses GFP_NOFS in this context, so we keep it consistent but it does
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* not seem to be strictly necessary.
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*/
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nofs_flag = memalloc_nofs_save();
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ipath = init_ipath(4096, local_root, swarn->path);
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memalloc_nofs_restore(nofs_flag);
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if (IS_ERR(ipath)) {
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ret = PTR_ERR(ipath);
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ipath = NULL;
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