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hfs: prevent btree data loss on ENOSPC

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Inserting a new record in a btree may require splitting several of its
nodes.  If we hit ENOSPC halfway through, the new nodes will be left
orphaned and their records will be lost.  This could mean lost inodes or
extents.

Henceforth, check the available disk space before making any changes.
This still leaves the potential problem of corruption on ENOMEM.

There is no need to reserve space before deleting a catalog record, as we
do for hfsplus.  This difference is because hfs index nodes have fixed
length keys.

Link: http://lkml.kernel.org/r/ab5fc8a7d5ffccfd5f27b1cf2cb4ceb6c110da74.1536269131.git.ernesto.mnd.fernandez@gmail.com
Signed-off-by: Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Ernesto A. Fernández
2018-10-30 15:06:17 -07:00
committed by Linus Torvalds
parent d92915c35b
commit 54640c7502
4 changed files with 49 additions and 19 deletions
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4
fs/hfs/extent.c
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@@ -117,6 +117,10 @@ static int __hfs_ext_write_extent(struct inode *inode, struct hfs_find_data *fd)
if (HFS_I(inode)->flags & HFS_FLG_EXT_NEW) {
if (res != -ENOENT)
return res;
/* Fail early and avoid ENOSPC during the btree operation */
res = hfs_bmap_reserve(fd->tree, fd->tree->depth + 1);
if (res)
return res;
hfs_brec_insert(fd, HFS_I(inode)->cached_extents, sizeof(hfs_extent_rec));
HFS_I(inode)->flags &= ~(HFS_FLG_EXT_DIRTY|HFS_FLG_EXT_NEW);
} else {