fs/msdosfs fatblock: use ulmin() rather than min()

to avoid truncation of pmp->pm_FATsecs.

Submitted by: Robert Morris <rtm@lcs.mit.edu>
PR: 277237
MFC after: 1 week

sys: Remove $FreeBSD$: one-line .c comment pattern

Remove /^/[*/]\s*\$FreeBSD\$.*\n/

fs/msdosfs: Fix potential panic and size calculations

Some combinations of FAT12 file system parameters could cause a kernel
panic due to an unmapped access if the size of the FAT was larger than
th

fs/msdosfs: Fix potential panic and size calculations

Some combinations of FAT12 file system parameters could cause a kernel
panic due to an unmapped access if the size of the FAT was larger than
the CPU page size. The reason is that FAT12 uses 3 bytes to store
2 FAT pointers, leading to partial FAT pointers at the end of buffers
of a size that is not a multiple of 3.

With a typical page size of 4 KB, this caused the FAT entry at byte
offsets 4095 and 4096 to cross the page boundary, with only the first
page mapped. This was fixed by adjusting the mapping to always cover
both bytes of each FAT entry.

Testing revealed 2 other inconsistencies that are fixed by this commit:

1) The calculation of the size of the data area did not take into
account the fact that the first two data block numbers are reserved
and that the data area starts with block 2. This could cause a
FAT12 file system created with the maximum supported number of
blocks to be incorrectly identified as FAT16.

2) The root directory does not take up space in the data area of a
FAT12 or FAT16 file system, since it is placed into a reserved
area outside of that data area. This commits makes stat() report
the logical size of the root directory, but with 0 blocks allocated
from the data area.

PR: 270587
Reviewed by: mckusick
Differential Revision: https://reviews.freebsd.org/D39386

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msdosfs: on integrity error, fire a task to remount filesystem to ro

In collaboration with: pho
Reviewed by: markj, mckusick
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revis

msdosfs: on integrity error, fire a task to remount filesystem to ro

In collaboration with: pho
Reviewed by: markj, mckusick
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D33721

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msdosfs: clusterfree() is used only in error handling cases

Change its return type to void, because its result is ignored in both
call sites. Remove oldcnp argument as well, it is NULL always.

Sug

msdosfs: clusterfree() is used only in error handling cases

Change its return type to void, because its result is ignored in both
call sites. Remove oldcnp argument as well, it is NULL always.

Suggested and reviewed by: markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D33721

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msdosfs: take inusemap inconsistency as an error, not invariants violation

In other words, stop silently accepting freeing free cluster in
non-debug kernels, but return the error to the caller. Mod

msdosfs: take inusemap inconsistency as an error, not invariants violation

In other words, stop silently accepting freeing free cluster in
non-debug kernels, but return the error to the caller. Modify callers
to handle errors from usemap_free().

In collaboration with: pho
Reviewed by: markj, mckusick
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D33721

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fs: clean up empty lines in .c and .h files

Plug the rest of undef behavior places that were missed in r337456.

There are three more places in msdosfs_fat.c which might shift one
into the sign bit. While there, fix formatting of KASSERTs.

S

Plug the rest of undef behavior places that were missed in r337456.

There are three more places in msdosfs_fat.c which might shift one
into the sign bit. While there, fix formatting of KASSERTs.

Sponsored by: The FreeBSD Foundation
MFC after: 1 week

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buf: Add B_INVALONERR flag to discard data

Setting the B_INVALONERR flag before a synchronous write causes the buf
cache to forcibly invalidate contents if the write fails (BIO_ERROR).

This is inte

buf: Add B_INVALONERR flag to discard data

Setting the B_INVALONERR flag before a synchronous write causes the buf
cache to forcibly invalidate contents if the write fails (BIO_ERROR).

This is intended to be used to allow layers above the buffer cache to make
more informed decisions about when discarding dirty buffers without
successful write is acceptable.

As a proof of concept, use in msdosfs to handle failures to mark the on-disk
'dirty' bit during rw mount or ro->rw update.

Extending this to other filesystems is left as future work.

PR: 210316
Reviewed by: kib (with objections)
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D21539

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msdosfs: Remove redundant brelse() after r294954

Same automation.

No functional change.

msdosfs: Drop an unneeded brelse in bread error condition

After r294954, it is an invariant that bread returns non-NULL bp if and only
if the routine succeeded. On error, it handles any buffer clea

msdosfs: Drop an unneeded brelse in bread error condition

After r294954, it is an invariant that bread returns non-NULL bp if and only
if the routine succeeded. On error, it handles any buffer cleanup
internally. So the brelse(NULL) here was just redundant.

No functional change.

Discussed with: kib (extracted from a larger differential)

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msdosfs_fat: reduce diffs with NetBSD and makefs

Use pointer arithmetic (as now done in makefs, and in NetBSD) instead of
taking the address of array element. No functional change, but this
makes i

msdosfs_fat: reduce diffs with NetBSD and makefs

Use pointer arithmetic (as now done in makefs, and in NetBSD) instead of
taking the address of array element. No functional change, but this
makes it easier to compare different versions of this file.

Reviewed by: kib
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D21365

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Add vn_fsync_buf().

Provide a convenience function to avoid the hack with filling fake
struct vop_fsync_args and then calling vop_stdfsync().

Sponsored by: The FreeBSD Foundation
MFC after: 1 week

Fix dirty buf exhaustion easily triggered with msdosfs.

If truncate(2) is performed on msdosfs file, which extends the file by
system-depended large amount, fs creates corresponding amount of dirty

Fix dirty buf exhaustion easily triggered with msdosfs.

If truncate(2) is performed on msdosfs file, which extends the file by
system-depended large amount, fs creates corresponding amount of dirty
delayed-write buffers, which can consume all buffers. Such buffers
cannot be flushed by the bufdaemon because the ftruncate() thread owns
the vnode lock. So the system runs out of free buffers, and even
truncate() thread starves, which means deadlock because it owns the
vnode lock.

Fix this by doing vnode fsync in extendfile() when low memory or low
buffers condition detected, which flushes all dirty buffers belonging
to the file being extended.

Note that the more usual fallback to bawrite() does not work
acceptable in this situation, because it would only allow one buffer
to be recycled. Other filesystems, most important UFS, do not allow
userspace to create arbitrary amount of dirty delayed-write buffers
without feedback, so bawrite() is good enough for them.

Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week

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msdosfs: fixes for Undefined Behavior.

These were found by the Undefined Behaviour GsoC project at NetBSD:

Do not change signedness bit with left shift.
While there avoid signed integer overflow.
A

msdosfs: fixes for Undefined Behavior.

These were found by the Undefined Behaviour GsoC project at NetBSD:

Do not change signedness bit with left shift.
While there avoid signed integer overflow.
Address both issues with using unsigned type.

msdosfs_fat.c:512:42, left shift of 1 by 31 places cannot be represented
in type 'int'
msdosfs_fat.c:521:44, left shift of 1 by 31 places cannot be represented
in type 'int'
msdosfs_fat.c:744:14, left shift of 1 by 31 places cannot be represented
in type 'int'
msdosfs_fat.c:744:24, signed integer overflow: -2147483648 - 1 cannot be
represented in type 'int [20]'
msdosfs_fat.c:840:13, left shift of 1 by 31 places cannot be represented
in type 'int'
msdosfs_fat.c:840:36, signed integer overflow: -2147483648 - 1 cannot be
represented in type 'int [20]'

Detected with micro-UBSan in the user mode.

Hinted from: NetBSD (CVS 1.33)
MFC after: 2 weeks
Differenctial Revision: https://reviews.freebsd.org/D16615

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Revert change made in base r171522
(https://svnweb.freebsd.org/base?view=revision&revision=304232)
converting clrbuf() (which clears the entire buffer) to vfs_bio_clrbuf()
(which clears only the new

Revert change made in base r171522
(https://svnweb.freebsd.org/base?view=revision&revision=304232)
converting clrbuf() (which clears the entire buffer) to vfs_bio_clrbuf()
(which clears only the new pages that have been added to the buffer).

Failure to properly remove pages from the buffer cache can make
pages that appear not to need clearing to actually have bad random
data in them. See for example base r304232
(https://svnweb.freebsd.org/base?view=revision&revision=304232)
which noted the need to set B_INVAL and B_NOCACHE as well as clear
the B_CACHE flag before calling brelse() to release the buffer.

Rather than trying to find all the incomplete brelse() calls, it
is simpler, though more slightly expensive, to simply clear the
entire buffer when it is newly allocated.

PR: 213507
Submitted by: Damjan Jovanovic
Reviewed by: kib

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sys/fs: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error

sys/fs: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

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Style.

Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks

Verify that the BPB media descriptor and FAT ID match.

FAT specification requires that for valid FAT, FAT cluster 0 has a
specific value derived from the BPB media descriptor. The lowest
(little-en

Verify that the BPB media descriptor and FAT ID match.

FAT specification requires that for valid FAT, FAT cluster 0 has a
specific value derived from the BPB media descriptor. The lowest
(little-endian) byte must be equal to bpb.bpbMedia, other bits in the
cluster number must be all 1's. Implement the check to reduce the
chance of the randomly corrupted FAT to pass the mount attempt.

Submitted by: Siva Mahadevan <smahadevan@freebsdfoundation.org>
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D12124

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msdosfs: reformat a comment to reduce NetBSD diffs

msdosfs: use mem{cpy,move,set} instead of bcopy,bzero

This somewhat simplifies use of msdosfs code in userland (for makefs),
reduces diffs with NetBSD and is standard C as of C89.

Reviewed by: imp

msdosfs: use mem{cpy,move,set} instead of bcopy,bzero

This somewhat simplifies use of msdosfs code in userland (for makefs),
reduces diffs with NetBSD and is standard C as of C89.

Reviewed by: imp
MFC after: 1 month
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D11014

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msdosfs: capitalize FAT appropriately

Diff reduction with NetBSD, including some nearby minor whitespace or
style fixes.

Obtained from: NetBSD
Sponsored by: The FreeBSD Foundation

msdosfs: use C99 types

General cleanup, for diff reduction with NetBSD and future use by FAT
support in makefs.

Submitted by: Siva Mahadevan <smahadevan@freebsdfoundation.org>
Obtained from: NetBSD

msdosfs: use C99 types

General cleanup, for diff reduction with NetBSD and future use by FAT
support in makefs.

Submitted by: Siva Mahadevan <smahadevan@freebsdfoundation.org>
Obtained from: NetBSD
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D10821

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Ensure that cluster allocations never allocate clusters outside the
volume limits. In particular:
- Assert that usemap_alloc() and usemap_free() cluster number argument
is valid.
- In chainlength(

Ensure that cluster allocations never allocate clusters outside the
volume limits. In particular:
- Assert that usemap_alloc() and usemap_free() cluster number argument
is valid.
- In chainlength(), return 0 if cluster start is after the max cluster.
- In chainlength(), cut the calculated cluster chain length at the max
cluster.
- For true paranoia, after the pm_inusemap is calculated in
fillinusemap(), reset all bits in the array for clusters after the
max cluster, as in-use.

Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks

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If the fatchain() call in chainalloc() returned an error, revert
marking the cluster run as in-use.

Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks