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94d7c16cbb
At the beginning of ext4_move_extent(), we call ext4_discard_preallocations() to discard inode PAs of orig and donor inodes. But in the following case, blocks can be double freed, so move ext4_discard_preallocations() to the end of ext4_move_extents(). 1. Discard inode PAs of orig and donor inodes with ext4_discard_preallocations() in ext4_move_extents(). orig : [ DATA1 ] donor: [ DATA2 ] 2. While data blocks are exchanging between orig and donor inodes, new inode PAs is created to orig by other process's block allocation. (Since there are semaphore gaps in ext4_move_extents().) And new inode PAs is used partially (2-1). 2-1 Create new inode PAs to orig inode orig : [ DATA1 | used PA1 | free PA1 ] donor: [ DATA2 ] 3. Donor inode which has old orig inode's blocks is deleted after EXT4_IOC_MOVE_EXT finished (3-1, 3-2). So the block bitmap corresponds to old orig inode's blocks are freed. 3-1 After EXT4_IOC_MOVE_EXT finished orig : [ DATA2 | free PA1 ] donor: [ DATA1 | used PA1 ] 3-2 Delete donor inode orig : [ DATA2 | free PA1 ] donor: [ FREE SPACE(DATA1) | FREE SPACE(used PA1) ] 4. The double-free of blocks is occurred, when close() is called to orig inode. Because ext4_discard_preallocations() for orig inode frees used PA1 and free PA1, though used PA1 is already freed in 3. 4-1 Double-free of blocks is occurred orig : [ DATA2 | FREE SPACE(free PA1) ] donor: [ FREE SPACE(DATA1) | DOUBLE FREE(used PA1) ] Signed-off-by: Akira Fujita <a-fujita@rs.jp.nec.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> |
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| .. | ||
| acl.c | ||
| acl.h | ||
| balloc.c | ||
| bitmap.c | ||
| block_validity.c | ||
| dir.c | ||
| ext4_extents.h | ||
| ext4_jbd2.c | ||
| ext4_jbd2.h | ||
| ext4.h | ||
| extents.c | ||
| file.c | ||
| fsync.c | ||
| hash.c | ||
| ialloc.c | ||
| inode.c | ||
| ioctl.c | ||
| Kconfig | ||
| Makefile | ||
| mballoc.c | ||
| mballoc.h | ||
| migrate.c | ||
| move_extent.c | ||
| namei.c | ||
| resize.c | ||
| super.c | ||
| symlink.c | ||
| xattr_security.c | ||
| xattr_trusted.c | ||
| xattr_user.c | ||
| xattr.c | ||
| xattr.h | ||