Four minor thin provisioning fixes and correct and update dm-verity
documentation. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iQIcBAABAgAGBQJP8t5wAAoJEK2W1qbAHj1ngaoP/0rSfdmKnP+XFUNHKmYbXv/F 0kLMiFLQYWepbsW1+1t/e+VmssJcmJ8DlSt0DycCag3HpgwajM4MVAic5CDjEXkX 9ewbe2LbObY8aWdnzhe+gRN7jCKPH41u6bhBNWrcskoMksfqHlpBhnk37CVS4Z5G OpqqgUjSXfcI05q9fZdb9BV/SvvmPj9LDC1T9mg41/zG2vAwUTkmvd7lqTFaQH/i 35UhWANJkr5LuUHOwPqfBQSA0psPa0Z8BvAHAzW6StNurwMT/HCk/BSlCJ26rK+L UcojGShCRoGO4Bf/r+IDMvwhnKtJZWPxOwYwAwzPHT4pnNQ+cp9PANm5tbZrmVWt fZXAttdMDAiVL/iZ57AB07rLJUNYWUEfvR2YPHuBzN+aIMIs+7ORkonK5/NoQtI3 XzdaSaLIAjdWJsskwzZFK2bFXsFTJ/J1ptnADFlxcppT/93wQ9YOu6t2dMuxWkKa FCYsGikXIP6LinkNWVF6wmI5wwWXINEqMABe0PXFU0kzf8saAsFsjpWmt5j0Wsk+ nX2+x4wqaazrg48LuNsb6MH/7IgaSgX18NI+kjtULLs08Bnq7VfV+cD6XJcyJmg9 6Bk+1+7wjwf60o5ZYcFwIQd3L8oqG8jXSH0b48fDLzAN8POkZt3eASVAEsOVaqIR xulqeo55eO4OkdOSL3A+ =3VU9 -----END PGP SIGNATURE----- Merge tag 'dm-3.5-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm Pull device-mapper fixes from Alasdair G Kergon: "Four minor thin provisioning fixes and correct and update dm-verity documentation." * tag 'dm-3.5-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm: dm: verity fix documentation dm persistent data: fix allocation failure in space map checker init dm persistent data: handle space map checker creation failure dm persistent data: fix shadow_info_leak on dm_tm_destroy dm thin: commit metadata before creating metadata snapshot
This commit is contained in:
Linus Torvalds
commit
3492ee7274
5 changed files with 102 additions and 110 deletions
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@ -7,13 +7,13 @@ This target is read-only.
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Construction Parameters
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=======================
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<version> <dev> <hash_dev> <hash_start>
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<version> <dev> <hash_dev>
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<data_block_size> <hash_block_size>
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<num_data_blocks> <hash_start_block>
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<algorithm> <digest> <salt>
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<version>
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This is the version number of the on-disk format.
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This is the type of the on-disk hash format.
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0 is the original format used in the Chromium OS.
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The salt is appended when hashing, digests are stored continuously and
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@ -24,22 +24,22 @@ Construction Parameters
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padded with zeros to the power of two.
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<dev>
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This is the device containing the data the integrity of which needs to be
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This is the device containing data, the integrity of which needs to be
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checked. It may be specified as a path, like /dev/sdaX, or a device number,
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<major>:<minor>.
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<hash_dev>
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This is the device that that supplies the hash tree data. It may be
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This is the device that supplies the hash tree data. It may be
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specified similarly to the device path and may be the same device. If the
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same device is used, the hash_start should be outside of the dm-verity
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configured device size.
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same device is used, the hash_start should be outside the configured
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dm-verity device.
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<data_block_size>
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The block size on a data device. Each block corresponds to one digest on
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the hash device.
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The block size on a data device in bytes.
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Each block corresponds to one digest on the hash device.
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<hash_block_size>
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The size of a hash block.
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The size of a hash block in bytes.
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<num_data_blocks>
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The number of data blocks on the data device. Additional blocks are
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@ -65,7 +65,7 @@ Construction Parameters
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Theory of operation
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===================
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dm-verity is meant to be setup as part of a verified boot path. This
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dm-verity is meant to be set up as part of a verified boot path. This
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may be anything ranging from a boot using tboot or trustedgrub to just
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booting from a known-good device (like a USB drive or CD).
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@ -73,20 +73,20 @@ When a dm-verity device is configured, it is expected that the caller
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has been authenticated in some way (cryptographic signatures, etc).
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After instantiation, all hashes will be verified on-demand during
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disk access. If they cannot be verified up to the root node of the
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tree, the root hash, then the I/O will fail. This should identify
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tree, the root hash, then the I/O will fail. This should detect
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tampering with any data on the device and the hash data.
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Cryptographic hashes are used to assert the integrity of the device on a
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per-block basis. This allows for a lightweight hash computation on first read
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into the page cache. Block hashes are stored linearly-aligned to the nearest
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block the size of a page.
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into the page cache. Block hashes are stored linearly, aligned to the nearest
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block size.
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Hash Tree
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---------
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Each node in the tree is a cryptographic hash. If it is a leaf node, the hash
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is of some block data on disk. If it is an intermediary node, then the hash is
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of a number of child nodes.
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of some data block on disk is calculated. If it is an intermediary node,
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the hash of a number of child nodes is calculated.
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Each entry in the tree is a collection of neighboring nodes that fit in one
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block. The number is determined based on block_size and the size of the
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@ -110,63 +110,23 @@ alg = sha256, num_blocks = 32768, block_size = 4096
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On-disk format
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==============
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Below is the recommended on-disk format. The verity kernel code does not
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read the on-disk header. It only reads the hash blocks which directly
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follow the header. It is expected that a user-space tool will verify the
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integrity of the verity_header and then call dmsetup with the correct
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parameters. Alternatively, the header can be omitted and the dmsetup
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parameters can be passed via the kernel command-line in a rooted chain
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of trust where the command-line is verified.
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The verity kernel code does not read the verity metadata on-disk header.
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It only reads the hash blocks which directly follow the header.
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It is expected that a user-space tool will verify the integrity of the
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verity header.
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The on-disk format is especially useful in cases where the hash blocks
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are on a separate partition. The magic number allows easy identification
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of the partition contents. Alternatively, the hash blocks can be stored
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in the same partition as the data to be verified. In such a configuration
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the filesystem on the partition would be sized a little smaller than
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the full-partition, leaving room for the hash blocks.
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struct superblock {
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uint8_t signature[8]
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"verity\0\0";
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uint8_t version;
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1 - current format
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uint8_t data_block_bits;
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log2(data block size)
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uint8_t hash_block_bits;
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log2(hash block size)
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uint8_t pad1[1];
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zero padding
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uint16_t salt_size;
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big-endian salt size
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uint8_t pad2[2];
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zero padding
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uint32_t data_blocks_hi;
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big-endian high 32 bits of the 64-bit number of data blocks
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uint32_t data_blocks_lo;
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big-endian low 32 bits of the 64-bit number of data blocks
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uint8_t algorithm[16];
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cryptographic algorithm
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uint8_t salt[384];
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salt (the salt size is specified above)
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uint8_t pad3[88];
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zero padding to 512-byte boundary
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}
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Alternatively, the header can be omitted and the dmsetup parameters can
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be passed via the kernel command-line in a rooted chain of trust where
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the command-line is verified.
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Directly following the header (and with sector number padded to the next hash
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block boundary) are the hash blocks which are stored a depth at a time
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(starting from the root), sorted in order of increasing index.
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The full specification of kernel parameters and on-disk metadata format
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is available at the cryptsetup project's wiki page
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http://code.google.com/p/cryptsetup/wiki/DMVerity
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Status
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======
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V (for Valid) is returned if every check performed so far was valid.
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@ -174,21 +134,22 @@ If any check failed, C (for Corruption) is returned.
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Example
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=======
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Setup a device:
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dmsetup create vroot --table \
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"0 2097152 "\
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"verity 1 /dev/sda1 /dev/sda2 4096 4096 2097152 1 "\
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Set up a device:
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# dmsetup create vroot --readonly --table \
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"0 2097152 verity 1 /dev/sda1 /dev/sda2 4096 4096 262144 1 sha256 "\
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"4392712ba01368efdf14b05c76f9e4df0d53664630b5d48632ed17a137f39076 "\
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"1234000000000000000000000000000000000000000000000000000000000000"
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A command line tool veritysetup is available to compute or verify
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the hash tree or activate the kernel driver. This is available from
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the LVM2 upstream repository and may be supplied as a package called
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device-mapper-verity-tools:
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git://sources.redhat.com/git/lvm2
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http://sourceware.org/git/?p=lvm2.git
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http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/verity?cvsroot=lvm2
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the hash tree or activate the kernel device. This is available from
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the cryptsetup upstream repository http://code.google.com/p/cryptsetup/
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(as a libcryptsetup extension).
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veritysetup -a vroot /dev/sda1 /dev/sda2 \
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Create hash on the device:
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# veritysetup format /dev/sda1 /dev/sda2
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...
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Root hash: 4392712ba01368efdf14b05c76f9e4df0d53664630b5d48632ed17a137f39076
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Activate the device:
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# veritysetup create vroot /dev/sda1 /dev/sda2 \
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4392712ba01368efdf14b05c76f9e4df0d53664630b5d48632ed17a137f39076
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@ -2292,6 +2292,13 @@ static int process_reserve_metadata_snap_mesg(unsigned argc, char **argv, struct
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if (r)
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return r;
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r = dm_pool_commit_metadata(pool->pmd);
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if (r) {
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DMERR("%s: dm_pool_commit_metadata() failed, error = %d",
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__func__, r);
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return r;
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}
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r = dm_pool_reserve_metadata_snap(pool->pmd);
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if (r)
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DMWARN("reserve_metadata_snap message failed.");
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@ -8,6 +8,7 @@
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#include <linux/device-mapper.h>
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#include <linux/export.h>
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#include <linux/vmalloc.h>
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#ifdef CONFIG_DM_DEBUG_SPACE_MAPS
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@ -89,13 +90,23 @@ static int ca_create(struct count_array *ca, struct dm_space_map *sm)
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ca->nr = nr_blocks;
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ca->nr_free = nr_blocks;
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ca->counts = kzalloc(sizeof(*ca->counts) * nr_blocks, GFP_KERNEL);
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if (!nr_blocks)
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ca->counts = NULL;
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else {
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ca->counts = vzalloc(sizeof(*ca->counts) * nr_blocks);
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if (!ca->counts)
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return -ENOMEM;
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}
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return 0;
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}
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static void ca_destroy(struct count_array *ca)
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{
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vfree(ca->counts);
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}
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static int ca_load(struct count_array *ca, struct dm_space_map *sm)
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{
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int r;
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@ -126,12 +137,14 @@ static int ca_load(struct count_array *ca, struct dm_space_map *sm)
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static int ca_extend(struct count_array *ca, dm_block_t extra_blocks)
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{
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dm_block_t nr_blocks = ca->nr + extra_blocks;
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uint32_t *counts = kzalloc(sizeof(*counts) * nr_blocks, GFP_KERNEL);
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uint32_t *counts = vzalloc(sizeof(*counts) * nr_blocks);
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if (!counts)
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return -ENOMEM;
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if (ca->counts) {
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memcpy(counts, ca->counts, sizeof(*counts) * ca->nr);
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kfree(ca->counts);
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ca_destroy(ca);
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}
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ca->nr = nr_blocks;
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ca->nr_free += extra_blocks;
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ca->counts = counts;
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@ -151,11 +164,6 @@ static int ca_commit(struct count_array *old, struct count_array *new)
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return 0;
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}
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static void ca_destroy(struct count_array *ca)
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{
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kfree(ca->counts);
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}
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/*----------------------------------------------------------------*/
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struct sm_checker {
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@ -343,25 +351,25 @@ struct dm_space_map *dm_sm_checker_create(struct dm_space_map *sm)
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int r;
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struct sm_checker *smc;
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if (!sm)
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return NULL;
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if (IS_ERR_OR_NULL(sm))
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return ERR_PTR(-EINVAL);
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smc = kmalloc(sizeof(*smc), GFP_KERNEL);
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if (!smc)
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return NULL;
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return ERR_PTR(-ENOMEM);
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memcpy(&smc->sm, &ops_, sizeof(smc->sm));
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r = ca_create(&smc->old_counts, sm);
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if (r) {
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kfree(smc);
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return NULL;
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return ERR_PTR(r);
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}
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r = ca_create(&smc->counts, sm);
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if (r) {
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ca_destroy(&smc->old_counts);
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kfree(smc);
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return NULL;
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return ERR_PTR(r);
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}
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smc->real_sm = sm;
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@ -371,7 +379,7 @@ struct dm_space_map *dm_sm_checker_create(struct dm_space_map *sm)
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ca_destroy(&smc->counts);
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ca_destroy(&smc->old_counts);
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kfree(smc);
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return NULL;
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return ERR_PTR(r);
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}
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r = ca_commit(&smc->old_counts, &smc->counts);
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@ -379,7 +387,7 @@ struct dm_space_map *dm_sm_checker_create(struct dm_space_map *sm)
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ca_destroy(&smc->counts);
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ca_destroy(&smc->old_counts);
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kfree(smc);
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return NULL;
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return ERR_PTR(r);
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}
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return &smc->sm;
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@ -391,25 +399,25 @@ struct dm_space_map *dm_sm_checker_create_fresh(struct dm_space_map *sm)
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int r;
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struct sm_checker *smc;
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if (!sm)
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return NULL;
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if (IS_ERR_OR_NULL(sm))
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return ERR_PTR(-EINVAL);
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smc = kmalloc(sizeof(*smc), GFP_KERNEL);
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if (!smc)
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return NULL;
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return ERR_PTR(-ENOMEM);
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memcpy(&smc->sm, &ops_, sizeof(smc->sm));
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r = ca_create(&smc->old_counts, sm);
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if (r) {
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kfree(smc);
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return NULL;
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return ERR_PTR(r);
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}
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r = ca_create(&smc->counts, sm);
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if (r) {
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ca_destroy(&smc->old_counts);
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kfree(smc);
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return NULL;
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return ERR_PTR(r);
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}
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smc->real_sm = sm;
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@ -290,7 +290,16 @@ struct dm_space_map *dm_sm_disk_create(struct dm_transaction_manager *tm,
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dm_block_t nr_blocks)
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{
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struct dm_space_map *sm = dm_sm_disk_create_real(tm, nr_blocks);
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return dm_sm_checker_create_fresh(sm);
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struct dm_space_map *smc;
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if (IS_ERR_OR_NULL(sm))
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return sm;
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smc = dm_sm_checker_create_fresh(sm);
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if (IS_ERR(smc))
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dm_sm_destroy(sm);
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return smc;
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}
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EXPORT_SYMBOL_GPL(dm_sm_disk_create);
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@ -138,6 +138,9 @@ EXPORT_SYMBOL_GPL(dm_tm_create_non_blocking_clone);
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void dm_tm_destroy(struct dm_transaction_manager *tm)
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{
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if (!tm->is_clone)
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wipe_shadow_table(tm);
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kfree(tm);
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}
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EXPORT_SYMBOL_GPL(dm_tm_destroy);
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@ -344,8 +347,10 @@ static int dm_tm_create_internal(struct dm_block_manager *bm,
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}
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*sm = dm_sm_checker_create(inner);
|
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if (!*sm)
|
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if (IS_ERR(*sm)) {
|
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r = PTR_ERR(*sm);
|
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goto bad2;
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}
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} else {
|
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r = dm_bm_write_lock(dm_tm_get_bm(*tm), sb_location,
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||||
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@ -364,9 +369,11 @@ static int dm_tm_create_internal(struct dm_block_manager *bm,
|
|||
}
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*sm = dm_sm_checker_create(inner);
|
||||
if (!*sm)
|
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if (IS_ERR(*sm)) {
|
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r = PTR_ERR(*sm);
|
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goto bad2;
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}
|
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}
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|
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return 0;
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|
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|
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Loading…
Reference in a new issue