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resolve_path.go
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resolve_path.go
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// Copyright (c) 2015-2021, NVIDIA CORPORATION.
// SPDX-License-Identifier: Apache-2.0
package fs
import (
"fmt"
"strings"
"github.com/swiftstack/ProxyFS/blunder"
"github.com/swiftstack/ProxyFS/dlm"
"github.com/swiftstack/ProxyFS/inode"
"github.com/swiftstack/ProxyFS/logger"
"github.com/swiftstack/ProxyFS/utils"
)
type resolvePathOption uint32
const (
resolvePathFollowDirEntrySymlinks resolvePathOption = 1 << iota
resolvePathFollowDirSymlinks // Follow symlink in final pathanme component
resolvePathCreateMissingPathElements // Defaults created DirEntry to be a File
resolvePathDirEntryInodeMustBeDirectory //
resolvePathDirEntryInodeMustBeFile //
resolvePathDirEntryInodeMustBeSymlink //
resolvePathRequireExclusiveLockOnDirEntryInode //
resolvePathRequireExclusiveLockOnDirInode // Presumably only useful if resolvePathRequireExclusiveLockOnDirEntryInode also specified
resolvePathRequireSharedLockOnDirInode // Not valid if resolvePathRequireExclusiveLockOnDirInode also specified
)
func resolvePathOptionsCheck(optionsRequested resolvePathOption, optionsToCheckFor resolvePathOption) (
optionsRequestedIncludesCheckFor bool) {
optionsRequestedIncludesCheckFor = (optionsToCheckFor == (optionsToCheckFor & optionsRequested))
return
}
type heldLocksStruct struct {
exclusive map[inode.InodeNumber]*dlm.RWLockStruct
shared map[inode.InodeNumber]*dlm.RWLockStruct
}
func newHeldLocks() (heldLocks *heldLocksStruct) {
heldLocks = &heldLocksStruct{
exclusive: make(map[inode.InodeNumber]*dlm.RWLockStruct),
shared: make(map[inode.InodeNumber]*dlm.RWLockStruct),
}
return
}
func (heldLocks *heldLocksStruct) attemptExclusiveLock(inodeVolumeHandle inode.VolumeHandle, dlmCallerID dlm.CallerID, inodeNumber inode.InodeNumber) (retryRequired bool) {
var (
err error
inodeLock *dlm.RWLockStruct
ok bool
)
_, ok = heldLocks.exclusive[inodeNumber]
if ok {
retryRequired = false
return
}
inodeLock, ok = heldLocks.shared[inodeNumber]
if ok {
err = inodeLock.Unlock()
if nil != err {
logger.Fatalf("Failure unlocking a held LockID %s: %v", inodeLock.LockID, err)
}
delete(heldLocks.shared, inodeNumber)
}
inodeLock, err = inodeVolumeHandle.AttemptWriteLock(inodeNumber, dlmCallerID)
if nil != err {
retryRequired = true
return
}
heldLocks.exclusive[inodeNumber] = inodeLock
retryRequired = false
return
}
func (heldLocks *heldLocksStruct) attemptSharedLock(inodeVolumeHandle inode.VolumeHandle, dlmCallerID dlm.CallerID, inodeNumber inode.InodeNumber) (retryRequired bool) {
var (
err error
inodeLock *dlm.RWLockStruct
ok bool
)
_, ok = heldLocks.exclusive[inodeNumber]
if ok {
retryRequired = false
return
}
_, ok = heldLocks.shared[inodeNumber]
if ok {
retryRequired = false
return
}
inodeLock, err = inodeVolumeHandle.AttemptReadLock(inodeNumber, dlmCallerID)
if nil != err {
retryRequired = true
return
}
heldLocks.shared[inodeNumber] = inodeLock
retryRequired = false
return
}
func (heldLocks *heldLocksStruct) unlock(inodeNumber inode.InodeNumber) {
var (
err error
heldLock *dlm.RWLockStruct
ok bool
)
heldLock, ok = heldLocks.exclusive[inodeNumber]
if ok {
err = heldLock.Unlock()
if nil != err {
logger.Fatalf("Failure unlocking a held LockID %s: %v", heldLock.LockID, err)
}
delete(heldLocks.exclusive, inodeNumber)
return
}
heldLock, ok = heldLocks.shared[inodeNumber]
if ok {
err = heldLock.Unlock()
if nil != err {
logger.Fatalf("Failure unlocking a held LockID %s: %v", heldLock.LockID, err)
}
delete(heldLocks.shared, inodeNumber)
return
}
logger.Fatalf("Attempt to unlock a non-held Lock on inodeNumber 0x%016X", inodeNumber)
}
func (heldLocks *heldLocksStruct) free() {
var (
err error
heldLock *dlm.RWLockStruct
)
for _, heldLock = range heldLocks.exclusive {
err = heldLock.Unlock()
if nil != err {
logger.Fatalf("Failure unlocking a held LockID %s: %v", heldLock.LockID, err)
}
}
for _, heldLock = range heldLocks.shared {
err = heldLock.Unlock()
if nil != err {
logger.Fatalf("Failure unlocking a held LockID %s: %v", heldLock.LockID, err)
}
}
}
// resolvePath is used to walk the supplied path starting at the supplied DirInode and locate
// the "leaf" {Dir|File}Inode. Various options allow for traversing encountered SymlinkInodes as
// well as optionally creating missing Inodes along the way. The caller is allowed to hold locks
// at entry that will be used (and possibly upgraded from "shared" to "exclusive") as well as
// extended to include any additional locks obtained. All lock requests are attempted so as to
// always avoid deadlock and if attempts fail, retryRequired == TRUE will be returned and the
// caller will be responsible for releasing all held locks, backing off (via a delay), before
// restarting the sequence.
//
// The pattern should look something like this:
//
// tryLockBackoffContext = &tryLockBackoffContextStruct{}
//
// Restart:
//
// tryLockBackoffContext.backoff()
//
// heldLocks = newHeldLocks()
//
// dirInode, dirEntryInode, retryRequired, err =
// resolvePath(inode.RootDirInodeNumber, path, heldLocks, resolvePathFollowSymlnks|...)
//
// if retryRequired {
// heldLocks.free()
// goto Restart
// }
//
// // Do whatever needed to be done with returned [dirInode and] dirEntryInode
//
// heldLocks.free()
//
func (vS *volumeStruct) resolvePath(startingInodeNumber inode.InodeNumber, path string, heldLocks *heldLocksStruct, options resolvePathOption) (dirInodeNumber inode.InodeNumber, dirEntryInodeNumber inode.InodeNumber, dirEntryBasename string, dirEntryInodeType inode.InodeType, retryRequired bool, err error) {
var (
dirEntryInodeLock *dlm.RWLockStruct
dirEntryInodeLockAlreadyExclusive bool
dirEntryInodeLockAlreadyHeld bool
dirEntryInodeLockAlreadyShared bool
dirInodeLock *dlm.RWLockStruct
dirInodeLockAlreadyExclusive bool
dirInodeLockAlreadyHeld bool
dirInodeLockAlreadyShared bool
dlmCallerID dlm.CallerID
followSymlink bool
inodeVolumeHandle inode.VolumeHandle
internalErr error
pathSplit []string
pathSplitPart string
pathSplitPartIndex int
symlinkCount uint16
symlinkTarget string
)
// Setup default returns
dirInodeNumber = inode.InodeNumber(0)
dirEntryInodeNumber = inode.InodeNumber(0)
dirEntryBasename = ""
retryRequired = false
err = nil
// Validate options
if resolvePathOptionsCheck(options, resolvePathRequireExclusiveLockOnDirInode) && resolvePathOptionsCheck(options, resolvePathRequireSharedLockOnDirInode) {
err = blunder.NewError(blunder.InvalidArgError, "resolvePath(,,,options) includes both resolvePathRequireExclusiveLockOnDirInode & resolvePathRequireSharedLockOnDirInode")
return
}
if resolvePathOptionsCheck(options, resolvePathDirEntryInodeMustBeDirectory) {
if resolvePathOptionsCheck(options, resolvePathDirEntryInodeMustBeFile) || resolvePathOptionsCheck(options, resolvePathDirEntryInodeMustBeSymlink) {
err = blunder.NewError(blunder.InvalidArgError, "resolvePath(,,,options) cannot include more than one {resolvePathDirEntryInodeMustBeDirectory, resolvePathDirEntryInodeMustBeFile, resolvePathDirEntryInodeMustBeSymlink}")
return
}
} else if resolvePathOptionsCheck(options, resolvePathDirEntryInodeMustBeFile) && resolvePathOptionsCheck(options, resolvePathDirEntryInodeMustBeSymlink) {
err = blunder.NewError(blunder.InvalidArgError, "resolvePath(,,,options) cannot include more than one {resolvePathDirEntryInodeMustBeDirectory, resolvePathDirEntryInodeMustBeFile, resolvePathDirEntryInodeMustBeSymlink}")
return
}
// Setup shortcuts/contants
dlmCallerID = dlm.GenerateCallerID()
inodeVolumeHandle = vS.inodeVolumeHandle
// Prepare for SymlinkInode-restart handling on canonicalized path
symlinkCount = 0
pathSplit, internalErr = canonicalizePath(path)
RestartAfterFollowingSymlink:
if nil != internalErr {
err = blunder.NewError(blunder.InvalidArgError, "resolvePath(,\"%s\",,) invalid", path)
return
}
// Start loop from a ReadLock on startingInodeNumber
dirInodeNumber = inode.InodeNumber(0)
dirEntryInodeNumber = startingInodeNumber
dirEntryInodeLock, dirEntryInodeLockAlreadyExclusive = heldLocks.exclusive[dirEntryInodeNumber]
if dirEntryInodeLockAlreadyExclusive {
dirEntryInodeLockAlreadyHeld = true
dirEntryInodeLockAlreadyShared = false
} else {
dirEntryInodeLock, dirEntryInodeLockAlreadyShared = heldLocks.shared[dirEntryInodeNumber]
if dirEntryInodeLockAlreadyShared {
dirEntryInodeLockAlreadyHeld = true
} else {
dirEntryInodeLockAlreadyHeld = false
dirEntryInodeLock, internalErr = inodeVolumeHandle.AttemptReadLock(dirEntryInodeNumber, dlmCallerID)
if nil != internalErr {
retryRequired = true
return
}
}
}
if 0 == len(pathSplit) {
// Special case where path resolves to "/"
// Note: dirEntryInodeNumber == inode.RootDirInodeNumber
// Reject invalid options for the "/" case
if resolvePathOptionsCheck(options, resolvePathDirEntryInodeMustBeFile) ||
resolvePathOptionsCheck(options, resolvePathDirEntryInodeMustBeSymlink) ||
resolvePathOptionsCheck(options, resolvePathRequireExclusiveLockOnDirInode) ||
resolvePathOptionsCheck(options, resolvePathRequireSharedLockOnDirInode) {
err = blunder.NewError(blunder.InvalidArgError, "resolvePath(inode.RootDirInodeNumber,\"/\",,options) cannot satisfy options: 0x%08X", options)
return
}
// Attempt to obtain requested lock on "/"
if resolvePathOptionsCheck(options, resolvePathRequireExclusiveLockOnDirEntryInode) {
if !dirEntryInodeLockAlreadyExclusive {
if dirEntryInodeLockAlreadyShared {
// Promote heldLocks.shared dirEntryInodeLock to .exclusive
internalErr = dirEntryInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirEntryInodeLock.LockID, internalErr)
}
delete(heldLocks.shared, dirEntryInodeNumber)
dirEntryInodeLockAlreadyHeld = false
dirEntryInodeLockAlreadyShared = false
dirEntryInodeLock, internalErr = inodeVolumeHandle.AttemptWriteLock(dirEntryInodeNumber, dlmCallerID)
if nil != internalErr {
// Caller must call heldLocks.free(), "backoff", and retry
if !dirInodeLockAlreadyHeld {
internalErr = dirInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirInodeLock.LockID, internalErr)
}
}
retryRequired = true
return
}
heldLocks.exclusive[dirEntryInodeNumber] = dirEntryInodeLock
dirEntryInodeLockAlreadyExclusive = true
dirEntryInodeLockAlreadyHeld = true
} else {
// Promote temporary ReadLock dirEntryInodeLock to .exclusive
internalErr = dirEntryInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirEntryInodeLock.LockID, internalErr)
}
dirEntryInodeLock, internalErr = inodeVolumeHandle.AttemptWriteLock(dirEntryInodeNumber, dlmCallerID)
if nil != internalErr {
// Caller must call heldLocks.free(), "backoff", and retry
if !dirInodeLockAlreadyHeld {
internalErr = dirInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirInodeLock.LockID, internalErr)
}
}
retryRequired = true
return
}
heldLocks.exclusive[dirEntryInodeNumber] = dirEntryInodeLock
dirEntryInodeLockAlreadyExclusive = true
dirEntryInodeLockAlreadyHeld = true
}
}
} else {
if !dirEntryInodeLockAlreadyHeld {
// Promote temporary ReadLock dirEntryInodeLock to heldLocks.shared
heldLocks.shared[dirEntryInodeNumber] = dirEntryInodeLock
dirEntryInodeLockAlreadyHeld = true
dirEntryInodeLockAlreadyShared = true
}
}
return
}
// Now loop for each pathSplit part
for pathSplitPartIndex, pathSplitPart = range pathSplit {
// Shift dirEntryInode to dirInode as we recurse down pathSplit
if inode.InodeNumber(0) != dirInodeNumber {
if !dirInodeLockAlreadyHeld {
internalErr = dirInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirInodeLock.LockID, internalErr)
}
}
}
dirInodeNumber = dirEntryInodeNumber
dirInodeLock = dirEntryInodeLock
dirInodeLockAlreadyExclusive = dirEntryInodeLockAlreadyExclusive
dirInodeLockAlreadyHeld = dirEntryInodeLockAlreadyHeld
dirInodeLockAlreadyShared = dirEntryInodeLockAlreadyShared
// Lookup dirEntry
dirEntryBasename = pathSplitPart // In case this is the last pathSplitPart that needs to be returned
dirEntryInodeNumber, internalErr = inodeVolumeHandle.Lookup(dirInodeNumber, pathSplitPart)
if nil == internalErr {
// Lookup() succeeded... ensure we have at least a ReadLock on dirEntryInode
dirEntryInodeLock, dirEntryInodeLockAlreadyExclusive = heldLocks.exclusive[dirEntryInodeNumber]
if dirEntryInodeLockAlreadyExclusive {
dirEntryInodeLockAlreadyHeld = true
dirEntryInodeLockAlreadyShared = false
} else {
dirEntryInodeLock, dirEntryInodeLockAlreadyShared = heldLocks.shared[dirEntryInodeNumber]
if dirEntryInodeLockAlreadyShared {
dirEntryInodeLockAlreadyHeld = true
} else {
dirEntryInodeLockAlreadyHeld = false
dirEntryInodeLock, internalErr = inodeVolumeHandle.AttemptReadLock(dirEntryInodeNumber, dlmCallerID)
if nil != internalErr {
// Caller must call heldLocks.free(), "backoff", and retry
// But first, free locks not recorded in heldLocks (if any)
if !dirInodeLockAlreadyHeld {
internalErr = dirInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirInodeLock.LockID, internalErr)
}
}
retryRequired = true
return
}
}
}
// Handle SymlinkInode case if requested
dirEntryInodeType, internalErr = inodeVolumeHandle.GetType(dirEntryInodeNumber)
if nil != internalErr {
logger.Fatalf("resolvePath(): failed obtaining InodeType for some part of path \"%s\"", path)
}
if dirEntryInodeType == inode.SymlinkType {
if pathSplitPartIndex < (len(pathSplit) - 1) {
followSymlink = resolvePathOptionsCheck(options, resolvePathFollowDirSymlinks)
} else { // pathSplitPartIndex == (len(pathSplit) - 1)
followSymlink = resolvePathOptionsCheck(options, resolvePathFollowDirEntrySymlinks)
}
if followSymlink {
symlinkTarget, internalErr = inodeVolumeHandle.GetSymlink(dirEntryInodeNumber)
if nil != internalErr {
logger.Fatalf("resolvePath(): failure from inode.GetSymlink() on a known SymlinkInode: %v", err)
}
// Free locks not recorded in heldLocks (if any)
if !dirEntryInodeLockAlreadyHeld {
internalErr = dirEntryInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirEntryInodeLock.LockID, internalErr)
}
}
if !dirInodeLockAlreadyHeld {
internalErr = dirInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirInodeLock.LockID, internalErr)
}
}
// Enforce SymlinkMax setting
if 0 != globals.symlinkMax {
symlinkCount++
if symlinkCount > globals.symlinkMax {
err = blunder.NewError(blunder.TooManySymlinksError, "resolvePath(): exceeded SymlinkMax")
return
}
}
// Apply symlinkTarget to path, reCanonicalize resultant path, and restart
pathSplit, internalErr = reCanonicalizePathForSymlink(pathSplit, pathSplitPartIndex, symlinkTarget)
goto RestartAfterFollowingSymlink
} else {
// Not following SymlinkInode... so its a failure if not last pathSplitPart
if pathSplitPartIndex < (len(pathSplit) - 1) {
// But first, free locks not recorded in heldLocks (if any)
if !dirEntryInodeLockAlreadyHeld {
internalErr = dirEntryInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirEntryInodeLock.LockID, internalErr)
}
}
if !dirInodeLockAlreadyHeld {
internalErr = dirInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirInodeLock.LockID, internalErr)
}
}
err = blunder.NewError(blunder.InvalidArgError, "resolvePath(,\"%s\",,) invalid", path)
return
} else {
// Being the last pathSplitPart, ensure caller didn't require it to be a DirInode or FileInode
if resolvePathOptionsCheck(options, resolvePathDirEntryInodeMustBeDirectory) {
if !dirEntryInodeLockAlreadyHeld {
internalErr = dirEntryInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirEntryInodeLock.LockID, internalErr)
}
}
if !dirInodeLockAlreadyHeld {
internalErr = dirInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirInodeLock.LockID, internalErr)
}
}
err = blunder.NewError(blunder.InvalidArgError,
"resolvePath(,\"%s\",,) '%s' is not a directory "+
"stack:\n%s",
path, pathSplitPart, utils.MyStackTrace())
return
} else if resolvePathOptionsCheck(options, resolvePathDirEntryInodeMustBeFile) {
if !dirEntryInodeLockAlreadyHeld {
internalErr = dirEntryInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirEntryInodeLock.LockID, internalErr)
}
}
if !dirInodeLockAlreadyHeld {
internalErr = dirInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirInodeLock.LockID, internalErr)
}
}
err = blunder.NewError(blunder.InvalidArgError, "resolvePath(,\"%s\",,) did not find FileInode", path)
return
} else {
// SymlinkInode is ok
}
}
}
} else {
// Not a SymlinkInode... check if it's last pathSplitPart and, if so, of correct InodeType
if pathSplitPartIndex == (len(pathSplit) - 1) {
if resolvePathOptionsCheck(options, resolvePathDirEntryInodeMustBeDirectory) {
if dirEntryInodeType != inode.DirType {
if !dirEntryInodeLockAlreadyHeld {
internalErr = dirEntryInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirEntryInodeLock.LockID, internalErr)
}
}
if !dirInodeLockAlreadyHeld {
internalErr = dirInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirInodeLock.LockID, internalErr)
}
}
err = blunder.NewError(blunder.InvalidArgError,
"resolvePath(,\"%s\",,) '%s' is not a directory "+
"stack:\n%s",
path, pathSplitPart, utils.MyStackTrace())
return
}
} else if resolvePathOptionsCheck(options, resolvePathDirEntryInodeMustBeFile) {
if dirEntryInodeType != inode.FileType {
if !dirEntryInodeLockAlreadyHeld {
internalErr = dirEntryInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirEntryInodeLock.LockID, internalErr)
}
}
if !dirInodeLockAlreadyHeld {
internalErr = dirInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirInodeLock.LockID, internalErr)
}
}
err = blunder.NewError(blunder.InvalidArgError, "resolvePath(,\"%s\",,) did not find FileInode", path)
return
}
} else if resolvePathOptionsCheck(options, resolvePathDirEntryInodeMustBeSymlink) {
if dirEntryInodeType != inode.SymlinkType {
if !dirEntryInodeLockAlreadyHeld {
internalErr = dirEntryInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirEntryInodeLock.LockID, internalErr)
}
}
if !dirInodeLockAlreadyHeld {
internalErr = dirInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirInodeLock.LockID, internalErr)
}
}
err = blunder.NewError(blunder.InvalidArgError, "resolvePath(,\"%s\",,) did not find SymlinkInode", path)
return
}
} else {
// Any InodeType is ok
}
}
}
} else {
// Lookup() failed... is resolvePath() asked to create missing Inode?
if resolvePathOptionsCheck(options, resolvePathCreateMissingPathElements) {
// Cannot implicitly create a SymlinkInode for last pathSplitPart
if (pathSplitPartIndex == (len(pathSplit) - 1)) && resolvePathOptionsCheck(options, resolvePathDirEntryInodeMustBeSymlink) {
if !dirInodeLockAlreadyHeld {
internalErr = dirInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirInodeLock.LockID, internalErr)
}
}
err = blunder.NewError(blunder.InvalidArgError, "resolvePath(,\"%s\",,) did not find SymlinkInode", path)
return
}
// Must hold exclusive lock to create missing {Dir|File}Inode
if !dirInodeLockAlreadyExclusive {
if dirInodeLockAlreadyShared {
// Promote heldLocks.shared InodeLock to .exclusive
internalErr = dirInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirInodeLock.LockID, internalErr)
}
delete(heldLocks.shared, dirInodeNumber)
dirInodeLockAlreadyHeld = false
dirInodeLockAlreadyShared = false
dirInodeLock, internalErr = inodeVolumeHandle.AttemptWriteLock(dirInodeNumber, dlmCallerID)
if nil != internalErr {
// Caller must call heldLocks.free(), "backoff", and retry
retryRequired = true
return
}
heldLocks.exclusive[dirInodeNumber] = dirInodeLock
dirInodeLockAlreadyExclusive = true
dirInodeLockAlreadyHeld = true
} else {
// Promote temporary ReadLock to heldLocks.exclusive
internalErr = dirInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirInodeLock.LockID, internalErr)
}
dirInodeLock, internalErr = inodeVolumeHandle.AttemptWriteLock(dirInodeNumber, dlmCallerID)
if nil != internalErr {
// Caller must call heldLocks.free(), "backoff", and retry
retryRequired = true
return
}
heldLocks.exclusive[dirInodeNumber] = dirInodeLock
dirInodeLockAlreadyExclusive = true
dirInodeLockAlreadyHeld = true
}
}
// Create missing {Dir|File}Inode (cannot implicitly create a SymlinkInode)
if (pathSplitPartIndex < (len(pathSplit) - 1)) || resolvePathOptionsCheck(options, resolvePathDirEntryInodeMustBeDirectory) {
// Create a DirInode to be inserted
dirEntryInodeType = inode.DirType
dirEntryInodeNumber, internalErr = inodeVolumeHandle.CreateDir(inode.InodeMode(0777), inode.InodeRootUserID, inode.InodeGroupID(0))
if nil != internalErr {
err = blunder.NewError(blunder.PermDeniedError, "resolvePath(): failed to create a DirInode: %v", err)
return
}
} else { // (pathSplitPartIndex == (len(pathSplit) - 1)) && !resolvePathOptionsCheck(options, resolvePathDirEntryInodeMustBeDirectory)
if resolvePathOptionsCheck(options, resolvePathDirEntryInodeMustBeSymlink) {
// Cannot implicitly create a SymlinkInode
err = blunder.NewError(blunder.InvalidArgError, "resolvePath(): cannot create a missing SymlinkInode")
return
} else {
// Create a FileInode to be inserted
dirEntryInodeType = inode.FileType
dirEntryInodeNumber, internalErr = inodeVolumeHandle.CreateFile(inode.InodeMode(0666), inode.InodeRootUserID, inode.InodeGroupID(0))
if nil != internalErr {
err = blunder.NewError(blunder.PermDeniedError, "resolvePath(): failed to create a FileInode: %v", err)
return
}
}
}
// Obtain and record an exclusive lock on just created {Dir|File}Inode
dirEntryInodeLock, internalErr = inodeVolumeHandle.AttemptWriteLock(dirEntryInodeNumber, dlmCallerID)
if nil != internalErr {
logger.Fatalf("resolvePath(): failed to exclusively lock just-created Inode 0x%016X: %v", dirEntryInodeNumber, internalErr)
}
heldLocks.exclusive[dirEntryInodeNumber] = dirEntryInodeLock
dirEntryInodeLockAlreadyExclusive = true
dirEntryInodeLockAlreadyHeld = true
dirEntryInodeLockAlreadyShared = false
// Now insert created {Dir|File}Inode
internalErr = inodeVolumeHandle.Link(dirInodeNumber, pathSplitPart, dirEntryInodeNumber, false)
if nil != internalErr {
err = blunder.NewError(blunder.PermDeniedError, "resolvePath(): failed to Link created {Dir|File}Inode into path %s: %v", path, internalErr)
internalErr = inodeVolumeHandle.Destroy(dirEntryInodeNumber)
if nil != internalErr {
logger.Errorf("resolvePath(): failed to Destroy() created {Dir|File}Inode 0x%016X: %v", dirEntryInodeNumber, internalErr)
}
return
}
} else {
// Don't create missing Inode... so its a failure
// But first, free locks not recorded in heldLocks (if any)
if !dirInodeLockAlreadyHeld {
internalErr = dirInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirInodeLock.LockID, internalErr)
}
}
err = blunder.NewError(blunder.NotFoundError, "resolvePath(,\"%s\",,) invalid", path)
return
}
}
}
if resolvePathOptionsCheck(options, resolvePathRequireExclusiveLockOnDirEntryInode) {
if !dirEntryInodeLockAlreadyExclusive {
if dirEntryInodeLockAlreadyShared {
// Promote heldLocks.shared dirEntryInodeLock to .exclusive
internalErr = dirEntryInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirEntryInodeLock.LockID, internalErr)
}
delete(heldLocks.shared, dirEntryInodeNumber)
dirEntryInodeLockAlreadyHeld = false
dirEntryInodeLockAlreadyShared = false
dirEntryInodeLock, internalErr = inodeVolumeHandle.AttemptWriteLock(dirEntryInodeNumber, dlmCallerID)
if nil != internalErr {
// Caller must call heldLocks.free(), "backoff", and retry
if !dirInodeLockAlreadyHeld {
internalErr = dirInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirInodeLock.LockID, internalErr)
}
}
retryRequired = true
return
}
heldLocks.exclusive[dirEntryInodeNumber] = dirEntryInodeLock
dirEntryInodeLockAlreadyExclusive = true
dirEntryInodeLockAlreadyHeld = true
} else {
// Promote temporary ReadLock dirEntryInodeLock to .exclusive
internalErr = dirEntryInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirEntryInodeLock.LockID, internalErr)
}
dirEntryInodeLock, internalErr = inodeVolumeHandle.AttemptWriteLock(dirEntryInodeNumber, dlmCallerID)
if nil != internalErr {
// Caller must call heldLocks.free(), "backoff", and retry
if !dirInodeLockAlreadyHeld {
internalErr = dirInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirInodeLock.LockID, internalErr)
}
}
retryRequired = true
return
}
heldLocks.exclusive[dirEntryInodeNumber] = dirEntryInodeLock
dirEntryInodeLockAlreadyExclusive = true
dirEntryInodeLockAlreadyHeld = true
}
}
} else {
if !dirEntryInodeLockAlreadyHeld {
// Promote temporary ReadLock dirEntryInodeLock to heldLocks.shared
heldLocks.shared[dirEntryInodeNumber] = dirEntryInodeLock
dirEntryInodeLockAlreadyHeld = true
dirEntryInodeLockAlreadyShared = true
}
}
if resolvePathOptionsCheck(options, resolvePathRequireExclusiveLockOnDirInode) {
if !dirInodeLockAlreadyExclusive {
if dirInodeLockAlreadyShared {
// Promote heldLocks.shared dirInodeLock to .exclusive
internalErr = dirInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirInodeLock.LockID, internalErr)
}
delete(heldLocks.shared, dirInodeNumber)
dirInodeLockAlreadyHeld = false
dirInodeLockAlreadyShared = false
dirInodeLock, internalErr = inodeVolumeHandle.AttemptWriteLock(dirInodeNumber, dlmCallerID)
if nil != internalErr {
// Caller must call heldLocks.free(), "backoff", and retry
retryRequired = true
return
}
heldLocks.exclusive[dirInodeNumber] = dirInodeLock
dirInodeLockAlreadyExclusive = true
dirInodeLockAlreadyHeld = true
} else {
// Promote temporary ReadLock dirInodeLock to .exclusive
internalErr = dirInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirInodeLock.LockID, internalErr)
}
dirInodeLock, internalErr = inodeVolumeHandle.AttemptWriteLock(dirInodeNumber, dlmCallerID)
if nil != internalErr {
// Caller must call heldLocks.free(), "backoff", and retry
retryRequired = true
return
}
heldLocks.exclusive[dirInodeNumber] = dirInodeLock
dirInodeLockAlreadyExclusive = true
dirInodeLockAlreadyHeld = true
}
}
} else if resolvePathOptionsCheck(options, resolvePathRequireSharedLockOnDirInode) {
if !dirInodeLockAlreadyHeld {
// Promote temporary ReadLock dirInodeLock to .shared
heldLocks.shared[dirInodeNumber] = dirInodeLock
dirInodeLockAlreadyHeld = true
dirInodeLockAlreadyShared = true
}
} else {
if !dirInodeLockAlreadyHeld {
// If only temporary ReadLock dirInodeLock is held, release it
internalErr = dirInodeLock.Unlock()
if nil != internalErr {
logger.Fatalf("resolvePath(): failed unlocking held LockID %s: %v", dirInodeLock.LockID, internalErr)
}
}
}
return
}
func canonicalizePath(path string) (canonicalizedPathSplit []string, err error) {
var (
canonicalizedPathSplitLen int
pathSplit []string
pathSplitElement string
)
pathSplit = strings.Split(path, "/")
canonicalizedPathSplit = make([]string, 0, len(pathSplit))
for _, pathSplitElement = range pathSplit {
switch pathSplitElement {
case "":
// drop pathSplitElement
case ".":
// drop pathSplitElement
case "..":
// backup one pathSplitElement
canonicalizedPathSplitLen = len(canonicalizedPathSplit)
if 0 == canonicalizedPathSplitLen {
err = fmt.Errorf("\"..\" in path stepped beyond start of path")
return
}
canonicalizedPathSplit = canonicalizedPathSplit[:canonicalizedPathSplitLen-1]
default:
// append pathSplitElement
canonicalizedPathSplit = append(canonicalizedPathSplit, pathSplitElement)
}
}
err = nil
return
}
func reCanonicalizePathForSymlink(canonicalizedPathSplit []string, symlinkIndex int, symlinkTarget string) (reCanonicalizedPathSplit []string, err error) {
var (
updatedPath string
updatedPathAfterSymlink string
updatedPathBeforeSymlink string
)
if (0 == symlinkIndex) || strings.HasPrefix(symlinkTarget, "/") {
updatedPathBeforeSymlink = ""
} else {
updatedPathBeforeSymlink = strings.Join(canonicalizedPathSplit[:symlinkIndex], "/")
}
if len(canonicalizedPathSplit) == (symlinkIndex - 1) {
updatedPathAfterSymlink = ""
} else {
updatedPathAfterSymlink = strings.Join(canonicalizedPathSplit[symlinkIndex+1:], "/")
}
updatedPath = updatedPathBeforeSymlink + "/" + symlinkTarget + "/" + updatedPathAfterSymlink
reCanonicalizedPathSplit, err = canonicalizePath(updatedPath)
return
}
// canonicalizePathAndLocateLeafDirInode performs what canonicalizePath() does above but, in addition,
// locates the index in the resultant canonicalizedPathSplit where an existing directory resides. Note
// that no DLM Locks should be held at invocation as this func will be performing any necessary retries
// and would have no way of backing out of a caller's existing DLM locks.
//
// Returns:
// If canonicalPath is empty or invalid, err will be non-nil
// If path-located Inode exists,
// If path-located Inode is a DirInode, dirInodeIndex == len(canonicalizedPathSplit) - 1
// If path-located Inode is not a DirInode, dirInodeIndex == len(canonicalizedPathSplit) - 2
// If path-located Inode does not exist, dirInodeIndex == len(canonicalizedPathSplit) - 2
//
// Note 1: A dirInodeIndex == -1 is certainly possible and is, indeed, the expected result when
// parsing a path that directory refers to a Swift Container (i.e. root-level subdirectory).
//
// Note 2: No symbolic links will be followed. This is not a problem given that all we are really
// trying to indicate is if we know the path would resolve to a directory or not. It is
// certainly possible that the leaf element of the supplied path is a SymlinkInode pointing
// at a DirInode, but in that case it's still ok to begin searching from the DirInode
// containing the SymlinkInode (as in the case of MiddlewareGetContainer()'s use case).
//
// Note that a dirInodeIndex == -1 is possible
//
func (vS *volumeStruct) canonicalizePathAndLocateLeafDirInode(path string) (canonicalizedPathSplit []string, dirInodeIndex int, err error) {
var (
dirEntryInodeType inode.InodeType
heldLocks *heldLocksStruct
retryRequired bool
tryLockBackoffContext *tryLockBackoffContextStruct
)
canonicalizedPathSplit, err = canonicalizePath(path)
if nil != err {
return
}
if 0 == len(canonicalizedPathSplit) {
err = fmt.Errorf("Canonically empty path \"%s\" not allowed", path)
return
}
tryLockBackoffContext = &tryLockBackoffContextStruct{}
Restart:
tryLockBackoffContext.backoff()
heldLocks = newHeldLocks()
_, _, _, dirEntryInodeType, retryRequired, err =
vS.resolvePath(
inode.RootDirInodeNumber,
strings.Join(canonicalizedPathSplit, "/"),
heldLocks,